What are the uses of Java beans?

##1. Introduction to JavaBean

javaBean is a reusable component developed using the Java language. JavaBean can be used to reduce Repeat code to make the development of the entire JSP code more concise. Using JSP with JavaBean has the following advantages:

1. HTML and Java code can be separated, mainly for the convenience of future maintenance. If all the program code (HTML and Java) is written into the JSP page, the entire program code will be large and complex, causing difficulties in future maintenance.

2. You can take advantage of JavaBean. Write the programs you use every day as JavaBean components. When you want to use them in JSP, you only need to call the JavaBean components to perform the functions required by the user. You don't have to write the same program again, which can also save development time.

2. JavaBean development requirements

1. JavaBean itself is a class and belongs to Java object-oriented programming.

2. If you want to use the Javabean tags provided by JSP to operate simple classes in JSP, then this class must meet the following development requirements:

(1) All classes must be placed In a package, there is no package in the WEB;

(2) All classes must be declared as public class so that they can be accessed externally;

(3 ) All attributes in the class must be encapsulated, that is: use private declaration;

(4) If the encapsulated attributes need to be operated externally, the corresponding setter and getter methods must be written;

(5) There is at least one parameterless constructor in a JavaBean, which is used by tags in JSP.

The first simple JavaBean

package blog.csdn.joywy;  
public class SimpleBean{  
    private String name;  
    private int age;  
    public void setName(String name){  
        this.name = name;  
    }  
    public void setAge(int age){  
        this.age = age;  
    }  
    public String getName(){  
        return this.name;  
    }  
    public int getAge(){  
        return this.age;  
    }  
}

If a class only contains attributes, setters, and getter methods, then this class becomes a simple JavaBean.

There are also several nouns for simple JavaBeans:

(1)VO: Corresponding to simple Java objects, specially used for the operation of transferring values

(2)POJO: Simple Java object

(3)TO: Transmission object. When performing remote transmission, the class in which the object is located must implement the java.io.Serializable interface.

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