Java设计模式之Builder模式

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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;
?}}XmlBuilderpackage 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。