处理流
package chapter21.BufferedStream;
import java.io.BufferedReader;
import java.io.FileReader;
public class BufferedReader_ {
public static void main(String[] args) throws Exception {
String filePath="d:\\java\\code\\Hello.java";
//创建BufferedReader
BufferedReader bufferedReader = new BufferedReader(new FileReader(filePath));
//读取
String line;//按行读取，效率高 读取完返回null
while ((line = bufferedReader.readLine())!=null){
System.out.println(line);
}
bufferedReader.close();//只需关闭bufferedReader，底层FileReader会自动关闭
}
}
package chapter21.BufferedStream;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
public class BufferedWriter_ {
public static void main(String[] args) throws IOException {
String filePath="f:\\ok.txt";
//创建BufferedWriter
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(filePath));//filePath,true节点流上可追加
bufferedWriter.write("hello,666");
bufferedWriter.newLine(); //插入一个和系统相关的换行
bufferedWriter.write("hello,666");
bufferedWriter.close();//关闭外层即可。底层会自行关闭
}
}
Buffered拷贝
package chapter21.BufferedStream;
import java.io.*;
//按字符读取，不能操作二进制文件（声音、视频、doc、pdf），否则会造成文件损坏
public class BufferedCopy_ {
public static void main(String[] args) throws IOException {
String srcFilePath="d:\\java\\code\\Hello.java";
String destFilePath="d:\\java\\code\\Hello-.java";
BufferedReader bufferedReader = new BufferedReader(new FileReader(srcFilePath));
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(destFilePath));
//先读取
String line;
while ((line=bufferedReader.readLine())!=null){
//每读取一行遍写入
bufferedWriter.write(line);
bufferedWriter.newLine();//插入换行
}
System.out.println("已完成");
if (bufferedReader!=null){
bufferedReader.close();
}
if (bufferedWriter!=null){
bufferedWriter.close();
}
}
}
package chapter21.BufferedStream;
import java.io.*;
//按字节拷贝
public class BufferedCopy02 {
public static void main(String[] args) throws IOException {
String srcFilePath="d:\\java\\picture\\注释.png";
String desFilePath="d:\\java\\picture\\注释2.png";
BufferedInputStream bufferedInputStream = new BufferedInputStream(new FileInputStream(srcFilePath));
BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(new FileOutputStream(desFilePath));
//循环读取文件，写入desFilePath
byte[] buff=new byte[1024];
int readLen=0;
while ((readLen=bufferedInputStream.read(buff))!=-1){
bufferedOutputStream.write(buff,0,readLen);
}
System.out.println("拷贝成功");
//关闭流
if (bufferedInputStream!=null){
bufferedInputStream.close();
}
if (bufferedOutputStream!=null){
bufferedOutputStream.close();
}
}
}
对象处理流
package chapter21.ObjectStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
public class ObjectInputStream_ {
public static void main(String[] args) throws IOException, ClassNotFoundException {
String filePath="f:\\data.dat";//制定文件
ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(filePath));
//读取（反序列化）的顺序要和保存数据（序列化）的顺心一致，否则会异常
System.out.println(objectInputStream.readInt());
System.out.println(objectInputStream.readBoolean());
System.out.println(objectInputStream.readChar());
System.out.println(objectInputStream.readDouble());
System.out.println(objectInputStream.readUTF());//要按顺序，缺一不可（报错）
Object dog = objectInputStream.readObject();//对象里每个属性，成员对象都要实现接口序列化
System.out.println("运行类型"+dog.getClass());
System.out.println("dog信息"+dog);//object>dog
//关闭外层流，底层自动关闭
objectInputStream.close();
//如要调用dog类的成员
Dog dog2=(Dog) dog;//向下转型，不同包要引入
System.out.println(dog2.getName());
}
}
package chapter21.ObjectStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.Serializable;
public class ObjectOutStream_ {
public static void main(String[] args) throws IOException {
String filePath="f:\\data.dat";//序列化后，格式为dat
ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filePath));
//序列化数据到
oos.writeInt(100);//int>Integer(实现了Serializable)
oos.writeBoolean(true);//boolean>Boolean(实现了Serializable)
oos.writeChar('a');//char>Character(实现了Serializable)
oos.writeDouble(9.5);//double>Double(实现了Serializable)
oos.writeUTF("哈哈");//String (实现了Serializable)
oos.writeObject(new Dog("哈哈",10));//注意要实现Serializable接口
oos.close();
System.out.println("数据已保存（序列化形式）");
}
}
class Dog implements Serializable {
private String name;
private int age;
private static final long serialVersionUID=1L;//序列化版本号提高兼容性
public Dog(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public int getAge() {
return age;
}
@Override
public String toString() {
return "Dog{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}
标准输入输出流
package chapter21.Standard;
import java.util.Scanner;
public class InputAndOutput_ {
public static void main(String[] args) {
//标准输入 键盘
System.out.println(System.in.getClass());//System.in 编译类型Inputstream 运行类型BufferedInputStream
//标准输出 显示器
System.out.println(System.out.getClass());//System.out 编译类型Printstream 运行类型PrintStream
Scanner scanner = new Scanner(System.in);
String next= scanner.next();
System.out.println(next);
}
}
转换流
乱码引出转换流
package chapter21.Transformation;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
//默认情况下读取按照UTF-8读取
public class CodeQuestion {
public static void main(String[] args) throws IOException {
String filePath="f:\\a.txt";
BufferedReader br = new BufferedReader(new FileReader(filePath));
String s = br.readLine();
System.out.println("读取到的内容"+s);
br.close();
}
}
package chapter21.Transformation;
import java.io.*;
//解决编码问题引起的乱码
//字节流FileInputStream>>字符流InputStreamReader，指定编码
public class InputStreamReader_ {
public static void main(String[] args) throws IOException {
String filePath="f:\\a.txt";
//字节流FileInputStream>>字符流InputStreamReader 指定gbk编码
InputStreamReader isr = new InputStreamReader(new FileInputStream(filePath),"gbk");
//把InputStreamReader放入包装流BufferedReader
BufferedReader br = new BufferedReader(isr);
//读取
String s = br.readLine();
System.out.println("读取内容"+s);
//关闭流
br.close();
}
}
package chapter21.Transformation;
import java.io.*;
public class OutputStreamWriter_ {
public static void main(String[] args) throws IOException {
String filePath="f:\\a.txt";
String charSet="gbk";
OutputStreamWriter osw = new OutputStreamWriter(new FileOutputStream(filePath),charSet );
osw.write("hi,666");
osw.close();
System.out.println("按照"+charSet+"保存文件成功");
}
}
打印流
package chapter21.Print;
import java.io.IOException;
import java.io.PrintStream;
//PrintStream 字节打印流/输出流
public class PrintStream_ {
public static void main(String[] args) throws IOException {
PrintStream out=System.out;//System.out本身就是输出流，赋给PrintStream
out.print("666");
out.write("hhh".getBytes());//print底层用的write，所以可直接调用write打印
//修改打印输出的位置/设备
System.setOut(new PrintStream("f:\\f1.txt"));
System.out.println("666");//输出到f:\f1.txt
out.close();
}
}
package chapter21.Print;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;
public class PrintWriter_ {
public static void main(String[] args) throws IOException {
PrintWriter printWriter=new PrintWriter(System.out);
printWriter.print("hi,北京");
PrintWriter printWriter1 = new PrintWriter(new FileWriter("f:\\f2.txt"));
printWriter1.print("666");
printWriter.close();
printWriter1.close();//关闭流才能把数据写入文件
}
}
配置文件Properties
ip=192.168.100.100
user=root
pwd=123456
package chapter21.Properties;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
public class Properties01 {
public static void main(String[] args) throws IOException {
//读取文件，并获得相应ip
BufferedReader bufferedReader = new BufferedReader(new FileReader("d:\\java\\project\\JavaSE\\base\\src\\chapter21\\Properties\\mysql.properties"));
String line;
while ((line=bufferedReader.readLine())!=null){//按行读取
String[] split = line.split("=");//以"=”号拆分，拆成数组
if ("ip".equals(split[0])){
System.out.println(split[0]+"值是："+split[1]);//只打印ip
}
System.out.println(split[0]+"值是："+split[1]);
}
bufferedReader.close();
}
}
package chapter21.Properties;
import java.io.FileReader;
import java.io.IOException;
import java.util.Properties;
public class Properties02 {
public static void main(String[] args) throws IOException {
//使用Properties类读取mysql.properties文件
Properties properties = new Properties();//创建Properties对象
properties.load(new FileReader("d:\\java\\project\\JavaSE\\base\\src\\chapter21\\Properties\\mysql.properties"));//加载指定配置文件
properties.list(System.out);//K-V显示控制台
String user = properties.getProperty("user");//指定user输出
String pwd = properties.getProperty("pwd");
System.out.println("用户名"+user);
System.out.println("密码"+pwd);
}
}
#666
#Tue Jun 07 11:34:41 CST 2022
user=汤姆
pwd=888
charset=utf8
package chapter21.Properties;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;
public class Properties03 {
public static void main(String[] args) throws IOException {
//Properties创建修改配置文件
Properties properties = new Properties();//创建
properties.setProperty("charset","utf8");
properties.setProperty("user","汤姆");//中文unicode
properties.setProperty("pwd","abc111");
properties.setProperty("pwd","888");//已经有K则是修改 properties父类是Hashtable,底层就是Hashtable 核心方法
properties.store(new FileOutputStream("d:\\java\\project\\JavaSE\\base\\src\\chapter21\\Properties\\mysql2.properties"),"666");//K-V存到文件中 “666”注释
System.out.println("保存配置文件成功");
}
}
IO流章节作业
package chapter21.Homework;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
public class Homework01 {
public static void main(String[] args) throws IOException {
String Path="f:\\homework01";
File file = new File(Path);
if (!file.exists()){
if (file.mkdirs()){
System.out.println("创建"+Path+"创建成功");
}else {
System.out.println("创建失败");
}
}
String filePath=Path+"\\hello.txt";
file=new File(filePath);
if (!file.exists()){
if (file.createNewFile()){
System.out.println(filePath+"创建成功");
BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(file));
bufferedWriter.write("666");
bufferedWriter.close();
}else {
System.out.println(filePath+"创建失败");
}
}else {
System.out.println(filePath+"已经存在，不再创建。");
}
}
}
package chapter21.Homework;
import java.io.*;
public class Homework02 {
public static void main(String[] args) throws IOException {
String filePath="f:\\a.txt";
BufferedReader bufferedReader = new BufferedReader(new FileReader(filePath));//转换流的对象扔给bufferReader可以读取不同编码，解决乱码
BufferedReader bufferedReader1 = new BufferedReader(new InputStreamReader(new FileInputStream(filePath),"gbk"));
String line;
int lineNum=0;
while ((line=bufferedReader1.readLine())!=null){//按行读取
System.out.println(++lineNum+line);
}
if (bufferedReader1!=null){
bufferedReader1.close();
}
}
}
name=k
age=5
color=red
package chapter21.Homework;
import java.io.*;
import java.util.Properties;
public class Homework03 {
public static void main(String[] args) throws IOException, ClassNotFoundException {
String Path="d:\\java\\project\\JavaSE\\base\\src\\chapter21\\Homework\\dog.properties";
Properties properties = new Properties();
properties.load(new FileReader(Path));
String name = properties.get("name")+"";//object>string
int age = Integer.parseInt(properties.get("age")+"");//object>int
String color = properties.get("color") + "";//object>string
Dog dog = new Dog(name, age,color);
System.out.println(dog);
//序列化
String serPath="f:\\dog.dat";
ObjectOutputStream objectOutputStream = new ObjectOutputStream(new FileOutputStream(serPath));
objectOutputStream.writeObject(dog);
objectOutputStream.close();
System.out.println("dog对象序列化完成");
m1();
}
//反序列化
public static void m1() throws IOException, ClassNotFoundException {
String serPath="f:\\dog.dat";
ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(serPath));
Dog dog = (Dog) objectInputStream.readObject();
System.out.println(dog);
System.out.println("反序列完成");
objectInputStream.close();
}
}
class Dog implements Serializable {//序列化必须实现接口
private String name;
private int age;
private String color;
public Dog(String name, int age, String color) {
this.name = name;
this.age = age;
this.color = color;
}
@Override
public String toString() {
return "Dog{" +
"name='" + name + '\'' +
", age=" + age +
", color='" + color + '\'' +
'}';
}
}
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