1、AndroidManifest.xml
添加权限
<!-- 读取内存 -->
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<!-- 读取日志 -->
<permission android:name="android.permission.READ_LOGS" />
2、编写日志类
package com.liang.nano;
import android.content.Context;
import android.os.Environment;
import android.util.Log;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.text.SimpleDateFormat;
import java.util.Date;
public class LogcatHelper {
private static LogcatHelper INSTANCE = null;
private static String PATH_LOGCAT;
private LogDumper mLogDumper = null;
private int mPId;
/**
* 初始化目录
*/
public void init(Context context) {
if (Environment.getExternalStorageState().equals(
Environment.MEDIA_MOUNTED)) {// 优先保存到SD卡中
PATH_LOGCAT = Environment.getExternalStorageDirectory()
.getAbsolutePath() + File.separator + "aLog";
} else {// 如果SD卡不存在，就保存到本应用的目录下
PATH_LOGCAT = context.getFilesDir().getAbsolutePath()
+ File.separator + "aaLog";
}
File file = new File(PATH_LOGCAT);
Log.i("codedzh","存储位置："+PATH_LOGCAT);
if (!file.exists()) {
boolean mkdirs = file.mkdirs();
System.out.println(mkdirs);
}
Log.i("codedzh","文件是否存在："+new File(PATH_LOGCAT).exists());
}
public static LogcatHelper getInstance(Context context) {
if (INSTANCE == null) {
INSTANCE = new LogcatHelper(context);
}
return INSTANCE;
}
private LogcatHelper(Context context) {
init(context);
mPId = android.os.Process.myPid();
}
public void start() {
if (mLogDumper == null)
mLogDumper = new LogDumper(String.valueOf(mPId), PATH_LOGCAT);
mLogDumper.start();
}
public void stop() {
if (mLogDumper != null) {
mLogDumper.stopLogs();
mLogDumper = null;
}
}
private class LogDumper extends Thread {
private Process logcatProc;
private BufferedReader mReader = null;
private boolean mRunning = true;
String cmds = null;
private String mPID;
private FileOutputStream out = null;
public LogDumper(String pid, String dir) {
mPID = pid;
try {
out = new FileOutputStream(new File(dir, "log-"
+ getFileName() + ".log"));
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
/**
*
* 日志等级：*:v , *:d , *:w , *:e , *:f , *:s
*
* 显示当前mPID程序的 E和W等级的日志.
*
* */
// cmds = "logcat *:e *:w | grep \"(" + mPID + ")\"";
// cmds = "logcat | grep \"(" + mPID + ")\"";//打印所有日志信息
// cmds = "logcat -s way";//打印标签过滤信息
cmds = "logcat *:e *:i | grep \"(" + mPID + ")\"";
}
public void stopLogs() {
mRunning = false;
}
@Override
public void run() {
try {
logcatProc = Runtime.getRuntime().exec(cmds);
mReader = new BufferedReader(new InputStreamReader(
logcatProc.getInputStream()), 1024);
String line = null;
while (mRunning && (line = mReader.readLine()) != null) {
if (!mRunning) {
break;
}
if (line.length() == 0) {
continue;
}
if (out != null && line.contains(mPID)) {
out.write((line + "\n").getBytes());
}
}
} catch (IOException e) {
e.printStackTrace();
} finally {
if (logcatProc != null) {
logcatProc.destroy();
logcatProc = null;
}
if (mReader != null) {
try {
mReader.close();
mReader = null;
} catch (IOException e) {
e.printStackTrace();
}
}
if (out != null) {
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
out = null;
}
}
}
}
public String getFileName() {
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");
String date = format.format(new Date(System.currentTimeMillis()));
return date;
}
}
3、修改MainActivity
- 获取写权限
- 实例化日志类
public void onCreate(Bundle savedInstanceState)方法内添加
// 写权限
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
requestPermissions(new String[]{android.Manifest.permission.WRITE_EXTERNAL_STORAGE,android.Manifest.permission.READ_EXTERNAL_STORAGE},100);
}
// 实例化日志类
LogcatHelper.getInstance(this).start();
4、安装APP并授权（授权后需要重启app）
APP安装好之后打开，会弹出授权提醒，点击允许
注意：授权完之后需要重启APP，因为首次运行APP在初始化时还没有写权限，所以无法在设备内创建并写入日志文件
