import java.io.BufferedWriter;
import java.io.FileOutputStream;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.io.RandomAccessFile;
//如果文件存在，则追加内容；如果文件不存在，则创建文件，追加内容的三种方法
public class AppendContentToFile {
	public static void main(String[] args) {
		AppendContentToFile a = new AppendContentToFile();
		a.method1();
		a.method2("E:\\1.txt", "1");
		a.method3("E:\\2.txt", "2");
	}
}

public void method1() {
	FileWriter fw = null;
	try {
		//如果文件存在，则追加内容；如果文件不存在，则创建文件
		File f=new File("E:\\1.txt");
		fw = new FileWriter(f, true);
	} catch (IOException e) {
		e.printStackTrace();
	}
	PrintWriter pw = new PrintWriter(fw);
	pw.println("追加内容");
	pw.flush();
	try {
		fw.flush();
		pw.close();
		fw.close();
	} catch (IOException e) {
		e.printStackTrace();
	}
}

public static void method2(String file, String conent) {
	BufferedWriter out = null;
	try {
		out = new BufferedWriter(new OutputStreamWriter(
		new FileOutputStream(file, true)));
		out.write(conent+"\r\n");
	} catch (Exception e) {
		e.printStackTrace();
	} finally {
		try {
			out.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}

public static void method3(String fileName, String content) {
	try {
		// 打开一个随机访问文件流，按读写方式
		RandomAccessFile randomFile = new RandomAccessFile(fileName, "rw");
		// 文件长度，字节数
		long fileLength = randomFile.length();
		// 将写文件指针移到文件尾。
		randomFile.seek(fileLength);
		randomFile.writeBytes(content+"\r\n");
		randomFile.close();
	} catch (IOException e) {
		e.printStackTrace();
	}
	
}