标签：output int download data over 代码 family turn setw
看这两个类的名字就不难猜测出它们的类关系图。
DataOutputStream： 主要是一些writeXxx()操作，写出， 相当于序列化
DataInputStream： 主要是一些readXxx()操作，写入， 相当于反序列化
一般情况下，两者会成对出现。 在使用过程中要特别注意， 一个writeXxx() 对应着一个readXxx(), 千万不要用readInt()去对应writeBoolean().
说白了，就是序列化与反序列化要匹配。
下面举个例子，将Student对象的属性序列化后保存到文件中，然后反序列还原，示例代码如下：
public class Student { private int id; private String name; private long age; private boolean gender; public Student(int id, String name, long age, boolean gender) { this.id = id; this.name = name; this.age = age; this.gender = gender; } public int getId() { return id; } public void setId(int id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public long getAge() { return age; } public void setAge(long age) { this.age = age; } public boolean isGender() { return gender; } public void setGender(boolean gender) { this.gender = gender; } @Override public String toString() { return "Student{" + "id=" + id + ", name=‘" + name + ‘\‘‘ + ", age=" + age + ", gender=" + gender + ‘}‘; } }
@Test public void testDataStream() throws IOException { // 创建一个Student对象 Student student = new Student(1, "郑钦锋", 100, true); // 创建一个DataOutputStream对象 OutputStream outputStream = new FileOutputStream("E:\\360downloads\\wpcache\\srvsetwp\\student.txt"); DataOutputStream dataOutputStream = new DataOutputStream(outputStream); // 对java的8种基本数据类型进行write操作，其实就相当于序列化操作 dataOutputStream.writeInt(student.getId()); dataOutputStream.writeUTF(student.getName()); dataOutputStream.writeLong(student.getAge()); dataOutputStream.writeBoolean(student.isGender()); // 关流 dataOutputStream.close(); // 读取文件，进行反序列化操作 FileInputStream inputStream = new FileInputStream("E:\\360downloads\\wpcache\\srvsetwp\\student.txt"); DataInputStream dataInputStream = new DataInputStream(inputStream); int id = dataInputStream.readInt(); String name = dataInputStream.readUTF(); long age = dataInputStream.readLong(); boolean gender = dataInputStream.readBoolean(); // 还原这个student对象 Student retStudent = new Student(id, name, age, gender); System.out.println(retStudent); // Student{id=1, name=‘郑钦锋‘, age=100, gender=true} dataInputStream.close(); } }
如果序列化与反序列化不匹配，就是个悲剧，请看下面的示例：
@Test public void testDataStream() throws IOException { // 创建一个Student对象 Student student = new Student(1, "郑钦锋", 100, true); // 创建一个DataOutputStream对象 OutputStream outputStream = new FileOutputStream("E:\\360downloads\\wpcache\\srvsetwp\\student.txt"); DataOutputStream dataOutputStream = new DataOutputStream(outputStream); // 对java的8种基本数据类型进行write操作，其实就相当于序列化操作 dataOutputStream.writeLong(student.getAge()); dataOutputStream.writeBoolean(student.isGender()); dataOutputStream.writeUTF(student.getName()); dataOutputStream.writeInt(student.getId()); // 关流 dataOutputStream.close(); // 读取文件，进行反序列化操作 FileInputStream inputStream = new FileInputStream("E:\\360downloads\\wpcache\\srvsetwp\\student.txt"); DataInputStream dataInputStream = new DataInputStream(inputStream); int id = dataInputStream.readInt(); String name = dataInputStream.readUTF(); long age = dataInputStream.readLong(); boolean gender = dataInputStream.readBoolean(); // 还原这个student对象 Student retStudent = new Student(id, name, age, gender); System.out.println(retStudent); // Student{id=0, name=‘‘, age=28148597348991889, gender=true} dataInputStream.close(); }
所以，write序列化的顺序是： int(id) ---> string(name) ---> long(age)----> boolean(gender);
read反序列化的顺序一定要是： int(id) ---> string(name) ---> long(age)----> boolean(gender);
数据流:DataOutputStream与DataInputStream的使用
标签：output int download data over 代码 family turn setw
原文地址：https://www.cnblogs.com/z-qinfeng/p/11789786.html
