版权声明： https://blog.csdn.net/lfdfhl/article/details/27672913

MainActivity例如以下:

package cc.c;

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.util.List;

import android.app.Activity;

import android.app.ActivityManager;

import android.app.ActivityManager.MemoryInfo;

import android.app.ActivityManager.RunningAppProcessInfo;

import android.content.Context;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.TextView;

/**

 * Demo描写叙述:

 * 清理手机内存

 *

 * 參考资料:

 * 1 http://blog.30c.org/1816.html

 * 2 http://www.cnblogs.com/helloandroid/archive/2011/10/14/2212334.html

 *   Thank you very much

 *

 * 注意权限:

 * <uses-permission android:name="android.permission.KILL_BACKGROUND_PROCESSES" />

 *

 */

public class MainActivity extends Activity {

	private TextView mTotalMemoryTextView;

	private TextView mAvailMemoryTextView;

	private Button mCleanButton;

	private TextView mCleanInfoTextView;

	private ActivityManager mActivityManager;

	private StringBuffer mCleanInfoStringBuffer;

	private long availMemory;

	private long totalMemory;

	private List<RunningAppProcessInfo> mRunningAppProcessInfoList;

	@Override

	protected void onCreate(Bundle savedInstanceState) {

		super.onCreate(savedInstanceState);

		setContentView(R.layout.main);

		init();

	}

	private void init() {

		mCleanInfoStringBuffer = new StringBuffer();

		mActivityManager=(ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);

		mTotalMemoryTextView = (TextView) findViewById(R.id.totalMemoryTextView);

		mAvailMemoryTextView = (TextView) findViewById(R.id.availMemoryTextView);

		mCleanInfoTextView = (TextView) findViewById(R.id.cleanInfoTextView);

		mCleanButton = (Button) findViewById(R.id.cleanButton);

		totalMemory = getTotalMemory();

		availMemory = getAvailMemory();

		mTotalMemoryTextView.setText(totalMemory + "MB");

		mAvailMemoryTextView.setText(availMemory + "MB");

		mCleanButton.setOnClickListener(new View.OnClickListener() {

			@Override

			public void onClick(View v) {

				RunningAppProcessInfo runningAppProcessInfo=null;

				mRunningAppProcessInfoList= mActivityManager.getRunningAppProcesses();

				//List<ActivityManager.RunningServiceInfo> serviceInfos = mActivityManager.getRunningServices(100);

				if (mRunningAppProcessInfoList != null) {

					for (int i = 0; i < mRunningAppProcessInfoList.size(); ++i) {

						runningAppProcessInfo= mRunningAppProcessInfoList.get(i);

						// 一般数值大于RunningAppProcessInfo.IMPORTANCE_SERVICE

						// 的进程即为长时间未使用进程或者空进程

						// 一般数值大于RunningAppProcessInfo.IMPORTANCE_VISIBLE

						// 的进程都是非可见进程,即在后台执行

						if (runningAppProcessInfo.importance > RunningAppProcessInfo.IMPORTANCE_VISIBLE) {

							String[] pkgList = runningAppProcessInfo.pkgList;

							for (int j = 0; j < pkgList.length; ++j) {

								mActivityManager.killBackgroundProcesses(pkgList[j]);

								mCleanInfoStringBuffer.append(pkgList[j] + " is killed...\n");

								mCleanInfoTextView.setText(mCleanInfoStringBuffer.toString());

							}

						}

					}

				}

                //再次获得剩余内存以计算清理值

				mCleanInfoStringBuffer.append("共清理："+(getAvailMemory() - availMemory) + "MB");

				mCleanInfoTextView.setText(mCleanInfoStringBuffer.toString());

				mAvailMemoryTextView.setText(getAvailMemory() + "MB");

			}

		});

	}

	private long getTotalMemory() {

		//系统的内存信息文件

		String filePath = "/proc/meminfo";

		String lineString;

		String[] stringArray;

		long totalMemory = 0;

		try {

			FileReader fileReader = new FileReader(filePath);

			BufferedReader bufferedReader = new BufferedReader(fileReader,1024 * 8);

			//读取meminfo第一行,获取系统总内存大小

			lineString = bufferedReader.readLine();

			//依照空格拆分

			stringArray = lineString.split("\\s+");

			//获得系统总内存,单位KB

			totalMemory = Integer.valueOf(stringArray[1]).intValue();

			bufferedReader.close();

			System.out.println("------> lineString=" + lineString+ ",stringArray[0]=" + stringArray[0] +

					           ",stringArray[1]="+ stringArray[1] + ",stringArray[2]=" + stringArray[2]);

		} catch (IOException e) {

		}

		return totalMemory / 1024;

	}

	private long getAvailMemory() {

		MemoryInfo memoryInfo = new MemoryInfo();

		mActivityManager.getMemoryInfo(memoryInfo);

		return memoryInfo.availMem / (1024 * 1024);

	}

}

main.xml例如以下:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:tools="http://schemas.android.com/tools"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin" >

    <TextView

        android:id="@+id/totalTextView"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="系统内存："

        android:textSize="25sp"

        android:textColor="#1cf109" />

    <TextView

        android:id="@+id/totalMemoryTextView"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_toRightOf="@id/totalTextView"

        android:textSize="25sp"

        android:textColor="#1cf109" />

    <TextView

        android:id="@+id/availTextView"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@id/totalTextView"

        android:text="可用内存："

        android:textSize="25sp"

        android:textColor="#5c0169" />

    <TextView

        android:id="@+id/availMemoryTextView"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_below="@id/totalTextView"

        android:layout_toRightOf="@id/availTextView"

        android:textSize="25sp"

        android:textColor="#5c0169" />

    <Button

        android:id="@+id/cleanButton"

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:layout_below="@id/availMemoryTextView"

        android:textSize="25sp"

        android:text="清理内存" />

    <ScrollView

        android:layout_width="fill_parent"

        android:layout_height="wrap_content"

        android:layout_below="@id/cleanButton" >

        <TextView

            android:id="@+id/cleanInfoTextView"

            android:layout_width="fill_parent"

            android:layout_height="wrap_content" />

    </ScrollView>

</RelativeLayout>

PS:更好的方式请參见Android清理设备内存具体完整演示样例(一)