Java设计形式之Builder模式

Java设计模式之Builder模式

关于Builder模式，网上盛传的例子就是那个buildPartA,buildPartB的程序，很少有其他的例子，看来真是天下文章一大抄！
下面是我自己写的一个例子，贴在这里。
定义一个文件生成器。文件的类:MyFile 分为三个部分，也就是说有三个属性：FileHead,FileContent,FileEnd。
FileHead定义如下：

package create.builder1;
public class FileHead {
private String value;

public String getValue() {
return value;
}

public void setValue(String value) {
this.value = value;
}
}

FileContent定义如下:

package create.builder1;
public class FileContent {
private String value;

public String getValue() {
return value;
}

public void setValue(String value) {
this.value = value;
}
}

FileEnd 定义如下：

package create.builder1;
public class FileEnd {
private String value;

public String getValue() {
return value;
}

public void setValue(String value) {
this.value = value;
}
}

现在定义MyFile:
package create.builder1;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.PrintWriter;

public class MyFile {
private FileHead fhead;

private FileContent fcontent;

private FileEnd fend;

public FileContent getFcontent() {
return fcontent;
}

public void setFcontent(FileContent fcontent) {
this.fcontent = fcontent;
}

public FileEnd getFend() {
return fend;
}

public void setFend(FileEnd fend) {
this.fend = fend;
}

public FileHead getFhead() {
return fhead;
}

public void setFhead(FileHead fhead) {
  this.fhead = fhead;
}
public void write(String path) throws IOException{
  File f=new File(path);
  FileWriter fw=new FileWriter(f);
  PrintWriter out=new PrintWriter(fw);
  out.println(fhead.getValue());
  out.println(fcontent.getValue());
  out.println(fend.getValue());
  out.close();
}
}

定义Builder，我给她取名字为FileBuilder:
package create.builder1;

public interface FileBuilder {
  void buildHead();
  void buildContent();
  void buildEnd();
  MyFile getResult();
}
该定义Director了，名字为：FileDirector:
package create.builder1;

public class FileDirector {
    private FileBuilder filebuilder;
    public FileDirector(FileBuilder filebuilder){
     this.filebuilder=filebuilder;
    }
    public void construct(){
     filebuilder.buildHead();
     filebuilder.buildContent();
     filebuilder.buildEnd();
    }
}

现在到了定义具体Builder的时候了，定义两个，一个是生成txt文件的，一个生成xml文件
TxtBuilder:
package create.builder1;

public class TxtBuilder implements FileBuilder{
private FileHead fh=new FileHead();
private FileContent fc=new FileContent();;
private FileEnd fe=new FileEnd();

public void buildHead() {
// TODO Auto-generated method stub
fh.setValue("This is text file");
}

public void buildContent() {
// TODO Auto-generated method stub
fc.setValue("this is my content");
}

public void buildEnd() {
// TODO Auto-generated method stub
fe.setValue("this is the end of the file");
}

public MyFile getResult() {
  // TODO Auto-generated method stub
  MyFile my=new MyFile();
  my.setFcontent(fc);
  my.setFhead(fh);
  my.setFend(fe);
  return my;
}

}

XmlBuilder

package create.builder1;

public class XmlBuilder implements FileBuilder {
    private FileHead fh=new FileHead();
    private FileContent fc=new FileContent();
    private FileEnd fe=new FileEnd();

public void buildHead() {
  // TODO Auto-generated method stub
  fh.setValue("<?xml version=\"1.0\" encoding=\"GB2312\"?><content>");
}

public void buildContent() {
// TODO Auto-generated method stub
fc.setValue("<test>asdasd</test>");
}

public void buildEnd() {
// TODO Auto-generated method stub
fe.setValue("</content>");
}

public MyFile getResult() {
  // TODO Auto-generated method stub
  MyFile my=new MyFile();
  my.setFcontent(fc);
  my.setFhead(fh);
  my.setFend(fe);
  return my;
}

}
Demo如下：
package create.builder1;

import java.io.IOException;

public class Demo {

public static void main(String[] args) throws IOException {
  // TODO Auto-generated method stub
        FileBuilder fb=new TxtBuilder();
        FileDirector fd=new FileDirector(fb);

        fd.construct();
        MyFile my=fb.getResult();
        my.write("D:/test.txt");

        FileBuilder fbxml=new XmlBuilder();
        FileDirector fdxml=new FileDirector(fbxml);
        fdxml.construct();
        MyFile myxml=fbxml.getResult();
        myxml.write("D:/test1.xml");
}

}
在Demo里可以看到Builder模式的特点。

Java设计形式之Builder模式

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