一手遮天 Android - 优化: 强引用, 软引用, 弱引用
一手遮天 Android - 优化: 强引用, 软引用, 弱引用
示例如下:
/optimize/Demo1.java
/**
* 强引用 - 宁可 oom（out of memory）也不回收
* 软引用 - 快 oom（out of memory）的时候将被回收
* 弱引用 - 遇到 gc（garbage collection）就被回收
*/
package com.webabcd.androiddemo.optimize;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import com.webabcd.androiddemo.R;
import com.webabcd.androiddemo.utils.Helper;
import java.lang.ref.SoftReference;
import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
public class Demo1 extends AppCompatActivity {
private final String LOG_TAG = "optimize_Demo1";
private Button _button1;
private Button _button2;
private Button _button3;
private List<byte[]> _listStrong = new ArrayList<>();
private List<SoftReference<byte[]>> _listSoft = new ArrayList<>();
private List<WeakReference<byte[]>> _listWeak = new ArrayList<>();
private Thread _threadStrong;
private Thread _threadSoft;
private Thread _threadWeak;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_optimize_demo1);
_button1 = findViewById(R.id.button1);
_button2 = findViewById(R.id.button2);
_button3 = findViewById(R.id.button3);
_button1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
sampleStrong();
}
});
_button2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
sampleSoft();
}
});
_button3.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
sampleWeak();
}
});
}
// 强引用的示例
private void sampleStrong() {
stopAllThread();
_threadStrong = new Thread(new Runnable() {
@Override
public void run() {
try {
while (true) {
byte[] buffer = new byte[10 * 1024 * 1024];
_listStrong.add(buffer);
int countNull = 0;
int countObject = 0;
for (byte[] b : _listStrong) {
if (b == null) { // 为 null 则说明被回收了
countNull ++;
} else {
countObject ++;
}
}
// 强引用 - 宁可 oom（out of memory）也不回收
Helper.printMemoryLog(LOG_TAG);
Log.d(LOG_TAG, String.format(Locale.US, "强引用示例, 集合数据条数:%d, 有对象的条数:%d, 无对象的条数:%d", _listStrong.size(), countObject, countNull));
if (Thread.interrupted()) {
break;
}
Thread.sleep(1000);
}
} catch (InterruptedException e) {
Log.d(LOG_TAG, "线程被 interrupted 了");
}
}
});
_threadStrong.setName("thread_strong");
_threadStrong.setDaemon(true);
_threadStrong.start();
}
// 软引用的示例
private void sampleSoft() {
stopAllThread();
_threadSoft = new Thread(new Runnable() {
@Override
public void run() {
try {
while (true) {
byte[] buffer = new byte[10 * 1024 * 1024];
SoftReference<byte[]> bufferSoft = new SoftReference(buffer);
_listSoft.add(bufferSoft);
int countNull = 0;
int countObject = 0;
for (SoftReference<byte[]> sr : _listSoft) {
if (sr.get() == null) { // 为 null 则说明被回收了
countNull ++;
} else {
countObject ++;
}
}
// 软引用 - 快 oom（out of memory）的时候将被回收
Helper.printMemoryLog(LOG_TAG);
Log.d(LOG_TAG, String.format(Locale.US, "软引用示例, 集合数据条数:%d, 有对象的条数:%d, 无对象的条数:%d", _listSoft.size(), countObject, countNull));
if (Thread.interrupted()) {
break;
}
Thread.sleep(1000);
}
} catch (InterruptedException e) {
Log.d(LOG_TAG, "线程被 interrupted 了");
}
}
});
_threadSoft.setName("thread_soft");
_threadSoft.setDaemon(true);
_threadSoft.start();
}
// 弱引用的示例
private void sampleWeak() {
stopAllThread();
_threadWeak = new Thread(new Runnable() {
@Override
public void run() {
try {
while (true) {
byte[] buffer = new byte[10 * 1024 * 1024];
WeakReference<byte[]> bufferWeak = new WeakReference(buffer);
_listWeak.add(bufferWeak);
int countNull = 0;
int countObject = 0;
for (WeakReference<byte[]> wr : _listWeak) {
if (wr.get() == null) { // 为 null 则说明被回收了
countNull ++;
} else {
countObject ++;
}
}
// 弱引用 - 遇到 gc（garbage collection）就被回收
Helper.printMemoryLog(LOG_TAG);
Log.d(LOG_TAG, String.format(Locale.US, "弱引用示例, 集合数据条数:%d, 有对象的条数:%d, 无对象的条数:%d", _listWeak.size(), countObject, countNull));
if (Thread.interrupted()) {
break;
}
Thread.sleep(1000);
}
} catch (InterruptedException e) {
Log.d(LOG_TAG, "线程被 interrupted 了");
}
}
});
_threadWeak.setName("thread_weak");
_threadWeak.setDaemon(true);
_threadWeak.start();
}
private void stopAllThread() {
if (_threadStrong != null) {
_threadStrong.interrupt();
_threadStrong = null;
}
if (_threadSoft != null) {
_threadSoft.interrupt();
_threadSoft = null;
}
if (_threadWeak != null) {
_threadWeak.interrupt();
_threadWeak = null;
}
_listStrong.clear();
_listSoft.clear();
_listWeak.clear();
}
}
/layout/activity_optimize_demo1.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<Button
android:id="@+id/button1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="强引用的示例" />
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="软引用的示例" />
<Button
android:id="@+id/button3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="弱引用的示例" />
</LinearLayout>
