Android 开发技巧之Log写入文件

在Android开发的时候经常会遇到手机offline，影响日志的查看与分析。为此，我写了一个简单的类用于将日志写入文件中，便于以后调试的时候可以拿来使用：

package org.test;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;
import java.text.SimpleDateFormat;
import java.util.Date;

public class LogWriter {

private static LogWriter mLogWriter;

private static String mPath;

private static Writer mWriter;

private static SimpleDateFormat df;

private LogWriter(String file_path) {
this.mPath = file_path;
this.mWriter = null;
}

public static LogWriter open(String file_path) throws IOException {
if (mLogWriter == null) {
mLogWriter = new LogWriter(file_path);
}
File mFile = new File(mPath);
mWriter = new BufferedWriter(new FileWriter(mPath), 2048);
df = new SimpleDateFormat("[yy-MM-dd hh:mm:ss]: ");

return mLogWriter;
}

public void close() throws IOException {
mWriter.close();
}

public void print(String log) throws IOException {
mWriter.write(df.format(new Date()));
mWriter.write(log);
mWriter.write("\n");
mWriter.flush();
}

public void print(Class cls, String log) throws IOException { //如果还想看是在哪个类里可以用这个方法
mWriter.write(df.format(new Date()));
mWriter.write(cls.getSimpleName() + " ");
mWriter.write(log);
mWriter.write("\n");
mWriter.flush();
}

}

感觉在整个程序中进行写日志操作之后用到一个实例，所以我用了单例模式

使用这个类的代码：

private LogWriter mLogWriter;

public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

File logf = new File(Environment.getExternalStorageDirectory()
+ File.separator + "DemoLog.txt");

try {
mLogWriter = LogWriter.open(logf.getAbsolutePath());
} catch (IOException e) {
// TODO Auto-generated catch block
Log.d(tag, e.getMessage());
}

log("onCreate()");
}

public void log(String msg) {
Log.d(tag, msg);

try {
mLogWriter.print(AlarmManagerDemo.class, msg);
} catch (IOException e) {
// TODO Auto-generated catch block
Log.d(tag, e.getMessage());
}
}