Java中的字符流FileReader与FileWriter详解

public int read();

public int read(char[] cbuf);

import org.junit.jupiter.api.Test;
import java.io.FileReader;
import java.io.IOException;

@Test
public void readFile01(){
    String filePath = "E:\\test.txt";
    FileReader fileReader = null;//创建FileReader对象
    int data;
    try {
        fileReader= new FileReader(filePath);
        //循环读取
        while ((data = fileReader.read())!=-1){
            System.out.print((char) data);
        }
    } catch (IOException e) {
        e.getMessage();
    }finally {
        if (fileReader!=null){
            try {
                fileReader.close();//释放内存
            } catch (IOException e) {
                e.getMessage();
            }
        }
    }
}

@Test
public void readFile02() {
    String filePath = "E:\\test.txt";
    FileReader fileReader = null;//创建FileReader对象
    int readLen = 0;
    char[] buf = new char[8];
    try {
        fileReader = new FileReader(filePath);
        //
        while ((readLen = fileReader.read(buf)) != -1) {
            System.out.print(new String(buf, 0, readLen));
        }
    } catch (IOException e) {
        e.getMessage();
    } finally {
        if (fileReader != null) {
            try {
                fileReader.close();//释放内存
            } catch (IOException e) {
                e.getMessage();
            }
        }
    }
}

import org.junit.jupiter.api.Test;
import java.io.FileWriter;
import java.io.IOException;

@Test
public void WriteFile02() {
    String filePath = "E:\\test.txt";//操作的文件路径
    //创建FileWrite对象
    FileWriter fileWriter = null;
    char[] chars = {'a', 'b', 'c'};
    try {
        fileWriter = new FileWriter(filePath, true);
        fileWriter.write('a');//写入单个字符
        fileWriter.write(chars);//写入指定数组
        fileWriter.write("hello,world".toCharArray(), 0, 5); //写入字符数组的指定部分 写入hello
        fileWriter.write("Java");//写入整个字符串
        fileWriter.write("你好，世界",0,2);//写入字符串的指定部分
    } catch (IOException e) {
        e.getMessage();//输出异常l
    } finally {
        try {
            fileWriter.close();//释放资源
        } catch (IOException e) {
            e.getMessage();
        }
    }
}