本文整理自网络，侵删。
一、日志工具类 Log.java
public class L
{
private L()
{
/* 不可被实例化 */
throw new UnsupportedOperationException("Cannot be instantiated!");
}
// 是否需要打印bug，可以在application的onCreate函数里面初始化
public static boolean isDebug = true;
private static final String TAG = "DefaultTag";
// 下面四个是默认tag的函数
public static void i(String msg)
{
if (isDebug)
Log.i(TAG, msg);
}
public static void d(String msg)
{
if (isDebug)
Log.d(TAG, msg);
}
public static void e(String msg)
{
if (isDebug)
Log.e(TAG, msg);
}
public static void v(String msg)
{
if (isDebug)
Log.v(TAG, msg);
}
// 下面是传入自定义tag的函数
public static void i(String tag, String msg)
{
if (isDebug)
Log.i(tag, msg);
}
public static void d(String tag, String msg)
{
if (isDebug)
Log.i(tag, msg);
}
public static void e(String tag, String msg)
{
if (isDebug)
Log.i(tag, msg);
}
public static void v(String tag, String msg)
{
if (isDebug)
Log.i(tag, msg);
}
}
二、Toast统一管理类 Tost.java
public class T
{
private T()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
public static boolean isShow = true;
/**
* 短时间显示Toast
*/
public static void showShort(Context context, CharSequence message)
{
if (isShow)
Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
}
/**
* 短时间显示Toast
* @param message 要显示的字符串资源的id
*/
public static void showShort(Context context, int message)
{
if (isShow)
Toast.makeText(context, message, Toast.LENGTH_SHORT).show();
}
/**
* 长时间显示Toast
*/
public static void showLong(Context context, CharSequence message)
{
if (isShow)
Toast.makeText(context, message, Toast.LENGTH_LONG).show();
}
/**
* 长时间显示Toast
*/
public static void showLong(Context context, int message)
{
if (isShow)
Toast.makeText(context, message, Toast.LENGTH_LONG).show();
}
/**
* 自定义显示Toast时间
*/
public static void show(Context context, CharSequence message, int duration)
{
if (isShow)
Toast.makeText(context, message, duration).show();
}
/**
* 自定义显示Toast时间
*/
public static void show(Context context, int message, int duration)
{
if (isShow)
Toast.makeText(context, message, duration).show();
}
}
三、SharedPreferences封装类 SPUtils.java 和 PreferencesUtils.java
1. SPUtils.java
public class SPUtils
{
/**
* 保存在手机里面的文件名
*/
public static final String FILE_NAME = "share_data";
/**
* 保存数据的方法，我们需要拿到保存数据的具体类型，然后根据类型调用不同的保存方法
*
* @param context
* @param key
* @param object
*/
public static void put(Context context, String key, Object object)
{
SharedPreferences sp = context.getSharedPreferences(FILE_NAME,
Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
if (object instanceof String)
{
editor.putString(key, (String) object);
} else if (object instanceof Integer)
{
editor.putInt(key, (Integer) object);
} else if (object instanceof Boolean)
{
editor.putBoolean(key, (Boolean) object);
} else if (object instanceof Float)
{
editor.putFloat(key, (Float) object);
} else if (object instanceof Long)
{
editor.putLong(key, (Long) object);
} else
{
editor.putString(key, object.toString());
}
SharedPreferencesCompat.apply(editor);
}
/**
* 得到保存数据的方法，我们根据默认值得到保存的数据的具体类型，然后调用相对于的方法获取值
*
* @param context
* @param key
* @param defaultObject
* @return
*/
public static Object get(Context context, String key, Object defaultObject)
{
SharedPreferences sp = context.getSharedPreferences(FILE_NAME,
Context.MODE_PRIVATE);
if (defaultObject instanceof String)
{
return sp.getString(key, (String) defaultObject);
} else if (defaultObject instanceof Integer)
{
return sp.getInt(key, (Integer) defaultObject);
} else if (defaultObject instanceof Boolean)
{
return sp.getBoolean(key, (Boolean) defaultObject);
} else if (defaultObject instanceof Float)
{
return sp.getFloat(key, (Float) defaultObject);
} else if (defaultObject instanceof Long)
{
return sp.getLong(key, (Long) defaultObject);
}
return null;
}
/**
* 移除某个key值已经对应的值
* @param context
* @param key
*/
public static void remove(Context context, String key)
{
SharedPreferences sp = context.getSharedPreferences(FILE_NAME,
Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
editor.remove(key);
SharedPreferencesCompat.apply(editor);
}
/**
* 清除所有数据
* @param context
*/
public static void clear(Context context)
{
SharedPreferences sp = context.getSharedPreferences(FILE_NAME,
Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sp.edit();
editor.clear();
SharedPreferencesCompat.apply(editor);
}
/**
* 查询某个key是否已经存在
* @param context
* @param key
* @return
*/
public static boolean contains(Context context, String key)
{
SharedPreferences sp = context.getSharedPreferences(FILE_NAME,
Context.MODE_PRIVATE);
return sp.contains(key);
}
/**
* 返回所有的键值对
*
* @param context
* @return
*/
public static Map<String, ?> getAll(Context context)
{
SharedPreferences sp = context.getSharedPreferences(FILE_NAME,
Context.MODE_PRIVATE);
return sp.getAll();
}
/**
* 创建一个解决SharedPreferencesCompat.apply方法的一个兼容类
*
* @author zhy
*
*/
private static class SharedPreferencesCompat
{
private static final Method sApplyMethod = findApplyMethod();
/**
* 反射查找apply的方法
*
* @return
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
private static Method findApplyMethod()
{
try
{
Class clz = SharedPreferences.Editor.class;
return clz.getMethod("apply");
} catch (NoSuchMethodException e)
{
}
return null;
}
/**
* 如果找到则使用apply执行，否则使用commit
*
* @param editor
*/
public static void apply(SharedPreferences.Editor editor)
{
try
{
if (sApplyMethod != null)
{
sApplyMethod.invoke(editor);
return;
}
} catch (IllegalArgumentException e)
{
} catch (IllegalAccessException e)
{
} catch (InvocationTargetException e)
{
}
editor.commit();
}
}
}
对SharedPreference的使用做了建议的封装，对外公布出put，get，remove，clear等等方法；
注意一点，里面所有的commit操作使用了SharedPreferencesCompat.apply进行了替代，目的是尽可能的使用apply代替commit.
首先说下为什么，因为commit方法是同步的，并且我们很多时候的commit操作都是UI线程中，毕竟是IO操作，尽可能异步；
所以我们使用apply进行替代，apply异步的进行写入；
但是apply相当于commit来说是new API呢，为了更好的兼容，我们做了适配；
SharedPreferencesCompat也可以给大家创建兼容类提供了一定的参考
2. SPUtils.java
public class PreferencesUtils {
public static String PREFERENCE_NAME = "TrineaAndroidCommon";
private PreferencesUtils() {
throw new AssertionError();
}
/**
* put string preferences
*
* @param context
* @param key The name of the preference to modify
* @param value The new value for the preference
* @return True if the new values were successfully written to persistent storage.
*/
public static boolean putString(Context context, String key, String value) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putString(key, value);
return editor.commit();
}
/**
* get string preferences
*
* @param context
* @param key The name of the preference to retrieve
* @return The preference value if it exists, or null. Throws ClassCastException if there is a preference with this
* name that is not a string
* @see #getString(Context, String, String)
*/
public static String getString(Context context, String key) {
return getString(context, key, null);
}
/**
* get string preferences
*
* @param context
* @param key The name of the preference to retrieve
* @param defaultValue Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws ClassCastException if there is a preference with
* this name that is not a string
*/
public static String getString(Context context, String key, String defaultValue) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getString(key, defaultValue);
}
/**
* put int preferences
*
* @param context
* @param key The name of the preference to modify
* @param value The new value for the preference
* @return True if the new values were successfully written to persistent storage.
*/
public static boolean putInt(Context context, String key, int value) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putInt(key, value);
return editor.commit();
}
/**
* get int preferences
*
* @param context
* @param key The name of the preference to retrieve
* @return The preference value if it exists, or -. Throws ClassCastException if there is a preference with this
* name that is not a int
* @see #getInt(Context, String, int)
*/
public static int getInt(Context context, String key) {
return getInt(context, key, -);
}
/**
* get int preferences
*
* @param context
* @param key The name of the preference to retrieve
* @param defaultValue Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws ClassCastException if there is a preference with
* this name that is not a int
*/
public static int getInt(Context context, String key, int defaultValue) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getInt(key, defaultValue);
}
/**
* put long preferences
*
* @param context
* @param key The name of the preference to modify
* @param value The new value for the preference
* @return True if the new values were successfully written to persistent storage.
*/
public static boolean putLong(Context context, String key, long value) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putLong(key, value);
return editor.commit();
}
/**
* get long preferences
*
* @param context
* @param key The name of the preference to retrieve
* @return The preference value if it exists, or -. Throws ClassCastException if there is a preference with this
* name that is not a long
* @see #getLong(Context, String, long)
*/
public static long getLong(Context context, String key) {
return getLong(context, key, -);
}
/**
* get long preferences
*
* @param context
* @param key The name of the preference to retrieve
* @param defaultValue Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws ClassCastException if there is a preference with
* this name that is not a long
*/
public static long getLong(Context context, String key, long defaultValue) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getLong(key, defaultValue);
}
/**
* put float preferences
*
* @param context
* @param key The name of the preference to modify
* @param value The new value for the preference
* @return True if the new values were successfully written to persistent storage.
*/
public static boolean putFloat(Context context, String key, float value) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putFloat(key, value);
return editor.commit();
}
/**
* get float preferences
*
* @param context
* @param key The name of the preference to retrieve
* @return The preference value if it exists, or -. Throws ClassCastException if there is a preference with this
* name that is not a float
* @see #getFloat(Context, String, float)
*/
public static float getFloat(Context context, String key) {
return getFloat(context, key, -);
}
/**
* get float preferences
*
* @param context
* @param key The name of the preference to retrieve
* @param defaultValue Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws ClassCastException if there is a preference with
* this name that is not a float
*/
public static float getFloat(Context context, String key, float defaultValue) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getFloat(key, defaultValue);
}
/**
* put boolean preferences
*
* @param context
* @param key The name of the preference to modify
* @param value The new value for the preference
* @return True if the new values were successfully written to persistent storage.
*/
public static boolean putBoolean(Context context, String key, boolean value) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
SharedPreferences.Editor editor = settings.edit();
editor.putBoolean(key, value);
return editor.commit();
}
/**
* get boolean preferences, default is false
*
* @param context
* @param key The name of the preference to retrieve
* @return The preference value if it exists, or false. Throws ClassCastException if there is a preference with this
* name that is not a boolean
* @see #getBoolean(Context, String, boolean)
*/
public static boolean getBoolean(Context context, String key) {
return getBoolean(context, key, false);
}
/**
* get boolean preferences
*
* @param context
* @param key The name of the preference to retrieve
* @param defaultValue Value to return if this preference does not exist
* @return The preference value if it exists, or defValue. Throws ClassCastException if there is a preference with
* this name that is not a boolean
*/
public static boolean getBoolean(Context context, String key, boolean defaultValue) {
SharedPreferences settings = context.getSharedPreferences(PREFERENCE_NAME, Context.MODE_PRIVATE);
return settings.getBoolean(key, defaultValue);
}
}
四、单位转换类 DensityUtils.java
public class DensityUtils
{
private DensityUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
/**
* dp转px
*
* @param context
* @param val
* @return
*/
public static int dppx(Context context, float dpVal)
{
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
dpVal, context.getResources().getDisplayMetrics());
}
/**
* sp转px
*
* @param context
* @param val
* @return
*/
public static int sppx(Context context, float spVal)
{
return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,
spVal, context.getResources().getDisplayMetrics());
}
/**
* px转dp
*
* @param context
* @param pxVal
* @return
*/
public static float pxdp(Context context, float pxVal)
{
final float scale = context.getResources().getDisplayMetrics().density;
return (pxVal / scale);
}
/**
* px转sp
*
* @param fontScale
* @param pxVal
* @return
*/
public static float pxsp(Context context, float pxVal)
{
return (pxVal / context.getResources().getDisplayMetrics().scaledDensity);
}
}
TypedValue：
Container for a dynamically typed data value. Primarily used with Resources for holding resource values.
applyDimension(int unit, float value, DisplayMetrics metrics)：
Converts an unpacked complex data value holding a dimension to its final floating point value.
五、SD卡相关辅助类 SDCardUtils.java
public class SDCardUtils
{
private SDCardUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
/**
* 判断SDCard是否可用
*
* @return
*/
public static boolean isSDCardEnable()
{
return Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED);
}
/**
* 获取SD卡路径
*
* @return
*/
public static String getSDCardPath()
{
return Environment.getExternalStorageDirectory().getAbsolutePath()
+ File.separator;
}
/**
* 获取SD卡的剩余容量 单位byte
*
* @return
*/
public static long getSDCardAllSize()
{
if (isSDCardEnable())
{
StatFs stat = new StatFs(getSDCardPath());
// 获取空闲的数据块的数量
long availableBlocks = (long) stat.getAvailableBlocks() - ;
// 获取单个数据块的大小（byte）
long freeBlocks = stat.getAvailableBlocks();
return freeBlocks * availableBlocks;
}
return ;
}
/**
* 获取指定路径所在空间的剩余可用容量字节数，单位byte
*
* @param filePath
* @return 容量字节 SDCard可用空间，内部存储可用空间
*/
public static long getFreeBytes(String filePath)
{
// 如果是sd卡的下的路径，则获取sd卡可用容量
if (filePath.startsWith(getSDCardPath()))
{
filePath = getSDCardPath();
} else
{// 如果是内部存储的路径，则获取内存存储的可用容量
filePath = Environment.getDataDirectory().getAbsolutePath();
}
StatFs stat = new StatFs(filePath);
long availableBlocks = (long) stat.getAvailableBlocks() - ;
return stat.getBlockSize() * availableBlocks;
}
/**
* 获取系统存储路径
*
* @return
*/
public static String getRootDirectoryPath()
{
return Environment.getRootDirectory().getAbsolutePath();
}
}
StatFs 是Android提供的一个类：
Retrieve overall information about the space on a filesystem. This is a wrapper for Unix statvfs().
检索一个文件系统的整体信息空间。这是一个Unix statvfs() 包装器
六、屏幕相关辅助类 ScreenUtils.java
public class ScreenUtils
{
private ScreenUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
/**
* 获得屏幕高度
*
* @param context
* @return
*/
public static int getScreenWidth(Context context)
{
WindowManager wm = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
return outMetrics.widthPixels;
}
/**
* 获得屏幕宽度
*
* @param context
* @return
*/
public static int getScreenHeight(Context context)
{
WindowManager wm = (WindowManager) context
.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
return outMetrics.heightPixels;
}
/**
* 获得状态栏的高度
*
* @param context
* @return
*/
public static int getStatusHeight(Context context)
{
int statusHeight = -;
try
{
Class<?> clazz = Class.forName("com.android.internal.R$dimen");
Object object = clazz.newInstance();
int height = Integer.parseInt(clazz.getField("status_bar_height")
.get(object).toString());
statusHeight = context.getResources().getDimensionPixelSize(height);
} catch (Exception e)
{
e.printStackTrace();
}
return statusHeight;
}
/**
* 获取当前屏幕截图，包含状态栏
*
* @param activity
* @return
*/
public static Bitmap snapShotWithStatusBar(Activity activity)
{
View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
Bitmap bmp = view.getDrawingCache();
int width = getScreenWidth(activity);
int height = getScreenHeight(activity);
Bitmap bp = null;
bp = Bitmap.createBitmap(bmp, , , width, height);
view.destroyDrawingCache();
return bp;
}
/**
* 获取当前屏幕截图，不包含状态栏
*
* @param activity
* @return
*/
public static Bitmap snapShotWithoutStatusBar(Activity activity)
{
View view = activity.getWindow().getDecorView();
view.setDrawingCacheEnabled(true);
view.buildDrawingCache();
Bitmap bmp = view.getDrawingCache();
Rect frame = new Rect();
activity.getWindow().getDecorView().getWindowVisibleDisplayFrame(frame);
int statusBarHeight = frame.top;
int width = getScreenWidth(activity);
int height = getScreenHeight(activity);
Bitmap bp = null;
bp = Bitmap.createBitmap(bmp, , statusBarHeight, width, height
- statusBarHeight);
view.destroyDrawingCache();
return bp;
}
}
七、App相关辅助类 APPUtils.java
public class AppUtils
{
private AppUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
/**
* 获取应用程序名称
*/
public static String getAppName(Context context)
{
try
{
PackageManager packageManager = context.getPackageManager();
PackageInfo packageInfo = packageManager.getPackageInfo(
context.getPackageName(), );
int labelRes = packageInfo.applicationInfo.labelRes;
return context.getResources().getString(labelRes);
} catch (NameNotFoundException e)
{
e.printStackTrace();
}
return null;
}
/**
* [获取应用程序版本名称信息]
*
* @param context
* @return 当前应用的版本名称
*/
public static String getVersionName(Context context)
{
try
{
PackageManager packageManager = context.getPackageManager();
PackageInfo packageInfo = packageManager.getPackageInfo(
context.getPackageName(), );
return packageInfo.versionName;
} catch (NameNotFoundException e)
{
e.printStackTrace();
}
return null;
}
}
八、软键盘相关辅助类KeyBoardUtils.java
/**
* 打开或关闭软键盘
*/
public class KeyBoardUtils
{
/**
* 打卡软键盘
*
* @param mEditText 输入框
* @param mContext 上下文
*/
public static void openKeybord(EditText mEditText, Context mContext)
{
InputMethodManager imm = (InputMethodManager) mContext
.getSystemService(Context.INPUT_METHOD_SERVICE);
imm.showSoftInput(mEditText, InputMethodManager.RESULT_SHOWN);
imm.toggleSoftInput(InputMethodManager.SHOW_FORCED,
InputMethodManager.HIDE_IMPLICIT_ONLY);
}
/**
* 关闭软键盘
*
* @param mEditText 输入框
* @param mContext 上下文
*/
public static void closeKeybord(EditText mEditText, Context mContext)
{
InputMethodManager imm = (InputMethodManager) mContext
.getSystemService(Context.INPUT_METHOD_SERVICE);
imm.hideSoftInputFromWindow(mEditText.getWindowToken(), );
}
}
九、网络相关辅助类 NetUtils.java
public class NetUtils
{
private NetUtils()
{
/* cannot be instantiated */
throw new UnsupportedOperationException("cannot be instantiated");
}
/**
* 判断网络是否连接
*/
public static boolean isConnected(Context context)
{
ConnectivityManager connectivity = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
if (null != connectivity)
{
NetworkInfo info = connectivity.getActiveNetworkInfo();
if (null != info && info.isConnected())
{
if (info.getState() == NetworkInfo.State.CONNECTED)
{
return true;
}
}
}
return false;
}
/**
* 判断是否是wifi连接
*/
public static boolean isWifi(Context context)
{
ConnectivityManager cm = (ConnectivityManager) context
.getSystemService(Context.CONNECTIVITY_SERVICE);
if (cm == null)
return false;
return cm.getActiveNetworkInfo().getType() == ConnectivityManager.TYPE_WIFI;
}
/**
* 打开网络设置界面
*/
public static void openSetting(Activity activity)
{
Intent intent = new Intent("/");
ComponentName cm = new ComponentName("com.android.settings",
"com.android.settings.WirelessSettings");
intent.setComponent(cm);
intent.setAction("android.intent.action.VIEW");
activity.startActivityForResult(intent, );
}
}
十、Http相关辅助类 HttpUtils.java
/**
* Http请求的工具类
*/
public class HttpUtils
{
private static final int TIMEOUT_IN_MILLIONS = ;
public interface CallBack
{
void onRequestComplete(String result);
}
/**
* 异步的Get请求
*
* @param urlStr
* @param callBack
*/
public static void doGetAsyn(final String urlStr, final CallBack callBack)
{
new Thread()
{
public void run()
{
try
{
String result = doGet(urlStr);
if (callBack != null)
{
callBack.onRequestComplete(result);
}
} catch (Exception e)
{
e.printStackTrace();
}
};
}.start();
}
/**
* 异步的Post请求
* @param urlStr
* @param params
* @param callBack
* @throws Exception
*/
public static void doPostAsyn(final String urlStr, final String params,
final CallBack callBack) throws Exception
{
new Thread()
{
public void run()
{
try
{
String result = doPost(urlStr, params);
if (callBack != null)
{
callBack.onRequestComplete(result);
}
} catch (Exception e)
{
e.printStackTrace();
}
};
}.start();
}
/**
* Get请求，获得返回数据
*
* @param urlStr
* @return
* @throws Exception
*/
public static String doGet(String urlStr)
{
URL url = null;
HttpURLConnection conn = null;
InputStream is = null;
ByteArrayOutputStream baos = null;
try
{
url = new URL(urlStr);
conn = (HttpURLConnection) url.openConnection();
conn.setReadTimeout(TIMEOUT_IN_MILLIONS);
conn.setConnectTimeout(TIMEOUT_IN_MILLIONS);
conn.setRequestMethod("GET");
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
if (conn.getResponseCode() == )
{
is = conn.getInputStream();
baos = new ByteArrayOutputStream();
int len = -;
byte[] buf = new byte[];
while ((len = is.read(buf)) != -)
{
baos.write(buf, , len);
}
baos.flush();
return baos.toString();
} else
{
throw new RuntimeException(" responseCode is not ... ");
}
} catch (Exception e)
{
e.printStackTrace();
} finally
{
try
{
if (is != null)
is.close();
} catch (IOException e)
{
}
try
{
if (baos != null)
baos.close();
} catch (IOException e)
{
}
conn.disconnect();
}
return null ;
}
/**
* 向指定 URL 发送POST方法的请求
*
* @param url
* 发送请求的 URL
* @param param
* 请求参数，请求参数应该是 name=value&name=value 的形式。
* @return 所代表远程资源的响应结果
* @throws Exception
*/
public static String doPost(String url, String param)
{
PrintWriter out = null;
BufferedReader in = null;
String result = "";
try
{
URL realUrl = new URL(url);
// 打开和URL之间的连接
HttpURLConnection conn = (HttpURLConnection) realUrl
.openConnection();
// 设置通用的请求属性
conn.setRequestProperty("accept", "*/*");
conn.setRequestProperty("connection", "Keep-Alive");
conn.setRequestMethod("POST");
conn.setRequestProperty("Content-Type",
"application/x-www-form-urlencoded");
conn.setRequestProperty("charset", "utf-");
conn.setUseCaches(false);
// 发送POST请求必须设置如下两行
conn.setDoOutput(true);
conn.setDoInput(true);
conn.setReadTimeout(TIMEOUT_IN_MILLIONS);
conn.setConnectTimeout(TIMEOUT_IN_MILLIONS);
if (param != null && !param.trim().equals(""))
{
// 获取URLConnection对象对应的输出流
out = new PrintWriter(conn.getOutputStream());
// 发送请求参数
out.print(param);
// flush输出流的缓冲
out.flush();
}
// 定义BufferedReader输入流来读取URL的响应
in = new BufferedReader(
new InputStreamReader(conn.getInputStream()));
String line;
while ((line = in.readLine()) != null)
{
result += line;
}
} catch (Exception e)
{
e.printStackTrace();
}
// 使用finally块来关闭输出流、输入流
finally
{
try
{
if (out != null)
{
out.close();
}
if (in != null)
{
in.close();
}
} catch (IOException ex)
{
ex.printStackTrace();
}
}
return result;
}
}
十一、时间工具类 TimeUtils.java
public class TimeUtils {
public static final SimpleDateFormat DEFAULT_DATE_FORMAT =
new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
public static final SimpleDateFormat DATE_FORMAT_DATE =
new SimpleDateFormat("yyyy-MM-dd");
private TimeUtils() {
throw new AssertionError();
}
/**
* long time to string
*
* @param timeInMillis
* @param dateFormat
* @return
*/
public static String getTime(long timeInMillis, SimpleDateFormat dateFormat) {
return dateFormat.format(new Date(timeInMillis));
}
/**
* long time to string, format is {@link #DEFAULT_DATE_FORMAT}
*
* @param timeInMillis
* @return
*/
public static String getTime(long timeInMillis) {
return getTime(timeInMillis, DEFAULT_DATE_FORMAT);
}
/**
* get current time in milliseconds
*
* @return
*/
public static long getCurrentTimeInLong() {
return System.currentTimeMillis();
}
/**
* get current time in milliseconds, format is {@link #DEFAULT_DATE_FORMAT}
*
* @return
*/
public static String getCurrentTimeInString() {
return getTime(getCurrentTimeInLong());
}
/**
* get current time in milliseconds
*
* @return
*/
public static String getCurrentTimeInString(SimpleDateFormat dateFormat) {
return getTime(getCurrentTimeInLong(), dateFormat);
}
}
十二、文件工具类 FileUtils.java
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数据库系统概念 第6版
本书主要讲述了数据模型、基于对象的数据库和XML、数据存储和查询、事务管理、体系结构等方面的内容。
