AndroidStudio中Handler类的内存溢出风险

?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154

package com.test.king.xmlparser;   import android.annotation.SuppressLint; import android.app.Activity; import android.content.res.Resources; import android.os.Handler; import android.os.Message; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.TextView;   import org.xmlpull.v1.XmlPullParser; import org.xmlpull.v1.XmlPullParserException;   import java.io.IOException; import java.lang.ref.WeakReference; import java.util.ArrayList; import java.util.List;   public class MainActivity extends AppCompatActivity {     private static TextView tvContent;     private static final int MSG_FINISH=0x0001;     @Override     protected void onCreate(Bundle savedInstanceState) {         super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);         tvContent=findViewById(R.id.tv_content);       }       //内部类解决可能存在的内存溢出     /*     *、本文描述静态和非静态内部类的区别是非静态内部类持有外部类的引用。 2、内部类实例的持有对象的生命周期大于其外部类对象，那么就有可能导致内存泄露。 比如,要实例化一个超出activity生命周期的内部类对象， 避免使用非静态的内部类。建议使用静态内部类并且在内部类中持有外部类的弱引用。     *     * */     //静态内部类     private static class MyHandler extends Handler {         private final WeakReference<MainActivity> mActivity;         //构造方法         public MyHandler(MainActivity activity) {             mActivity = new WeakReference<MainActivity>(activity);//对外部类的弱引用         }         @Override         public void handleMessage(Message msg) {             MainActivity activity = mActivity.get();             if (activity != null) {                 switch (msg.what)                 {                     case MSG_FINISH:                         List<String> contents=(List<String>)msg.obj;                         //在主线程中显示                         for(String content:contents)                         {                             tvContent.append(content+"\n");                         }                         break;                 }             }         }     }     //new Handler对象处理消息，下文有引用     private final MyHandler mHandler = new MyHandler(this);     //警告     /*     private Handler handler=new Handler()     {         @Override         //重写handleMessage方法处理消息         public void handleMessage(Message msg) {             switch (msg.what)             {                 case MSG_FINISH:                     List<String> contents=(List<String>)msg.obj;                     //在主线程中显示                     for(String content:contents)                     {                         tvContent.append(content+"\n");                     }                     break;             }           }     };*/         public  void parser(View view) throws IOException, XmlPullParserException {      //常规方法      /*      List<String> contents=getPullParserContent(getResources(),R.xml.words);      for(String content:contents)      {          tvContent.append(content+"\n");      }*/      //解析XML可能需要耗费很长的时间，所以这里单独做一个子线程         new Thread()         {             @Override             //重写run方法             public void run()             {                 try {                     List<String> contents=getPullParserContent(getResources(),R.xml.words);                     //完成工作，通知主线程                     Message msg=mHandler.obtainMessage();//也可以new Message                     msg.what=MSG_FINISH;                     msg.obj=contents;                     mHandler.sendMessage(msg);                 } catch (IOException e) {                     e.printStackTrace();                 } catch (XmlPullParserException e) {                     e.printStackTrace();                 }             }         }.start();       }     private List<String> getPullParserContent(Resources res,int id) throws IOException, XmlPullParserException {         List<String> contents = null;         String tagName;         //XmlPullParser         XmlPullParser parser = res.getXml(id);         //Pull解析本质是SAX解析         int eventType = parser.getEventType();         while (eventType != XmlPullParser.END_DOCUMENT) {             switch (eventType) {                 case XmlPullParser.START_DOCUMENT:                     Log.i("Test", "START_DOCUMENT");                     contents=new ArrayList<String>();                     break;                 case XmlPullParser.END_DOCUMENT:                     break;                 case XmlPullParser.START_TAG:                     tagName = parser.getName();                     if (tagName.equals("word")) {                         String value = parser.getAttributeValue(0);                         contents.add(value);                         Log.i("Test", "START_TAG:" + tagName + " " + value);                     }                     break;                 case XmlPullParser.END_TAG:                     tagName = parser.getName();                     Log.i("Test", "END_TAG:" + tagName);                     break;             }             eventType = parser.next();         }         return contents;     } }