REST是一種跨平臺、跨語言的架構風格，RESTful Web Service是REST風格在Web領域的實現，JAX-RS標準是Java語言對RESTful Web Service的規範，Jersey是JAX-RS的參考實現，也是Java EE參考實現專案GlassFish的子專案；REST架構風格中各種抽象物件被描述為資源，資源的瞬時狀態稱為representation且可用XML/JSON/Atom等格式表示。RESTful Web Servcie也可以分解為類似MVC的三層結構，即資源、業務和資料訪問物件，資源位於最前端用於接收請求和返回響應；JAX-RS2.0中定義的標準方法包括DELETE、GET、HEAD、OPTIONS、POST和PUT。
 

IDE採用IntelliJ IDEA Community Edition 14.1.2，構建工具採用gradle，建立gradle專案後，目錄結構如下

由於本專案需要依賴jersey的相關包，因此作如下的配置，同時定義repositories為oschina映象，否則無法攔截到mavencentral()。

build.gradle檔案內容:

apply plugin: 'java'
apply plugin:'war'
version = '1.0'
repositories {
    maven {
        url 'http://maven.oschina.net/content/groups/public/'
 
}
}
dependencies {
    compile group:'org.glassfish.jersey.containers',name:'jersey-container-grizzly2-http',version:'2.17'
compile group:'org.glassfish.jersey.media',name:'jersey-media-json-jackson',version:'2.17'
testCompile group: 'junit', name: 'junit', version: '4.11'
}

實體層：

@XmlRootElement(name="book"
 
)
public class Book {
    Integer id;
    String author;
    String bookName;
    String publisher;
    int price;

    public Book(Integer id, String author, String bookName, String publisher, int price) {
        this.id = id;
        this.author = author;
        this.bookName = bookName;
        this.publisher = publisher;
        this.price = price;
    }

    public void setId(Integer id){
        this.id=id;
    }
    @XmlAttribute
public Integer getId(){
        return id;
    }
    @XmlAttribute
public int getPrice() {
        return price;
    }

    public void setPrice(int price) {
        this.price = price;
    }
    @XmlAttribute
public String getAuthor() {
        return author;
    }

    public void setAuthor(String author) {
        this.author = author;
    }
    @XmlAttribute
public String getBookName() {
        return bookName;
    }

    public void setBookName(String bookName) {
        this.bookName = bookName;
    }
    @XmlAttribute
public String getPublisher() {
        return publisher;
    }

    public void setPublisher(String publisher) {
        this.publisher = publisher;
    }
}

DAO層：

public class BookDao {
    Map<Integer,Book> books=new HashMap<Integer,Book>();
    private static int nextId=7;
    public BookDao(){

        books.put(1,new Book(1,"張三","C語言程式設計","簡單出版社",29));
        books.put(2, new Book(2, "張三", "Java語言程式設計", "資訊出版社", 43));
        books.put(3, new Book(3, "李四", "大學物理", "教育出版社", 22));
        books.put(4, new Book(4, "李四", "高等數學", "教育出版社", 43));
        books.put(5, new Book(5, "孔子", "論語", "春秋出版社", 53));
        books.put(6, new Book(6, "福布斯", "大學英語", "未名出版社", 22));
    }
    public Book get(Integer id){
        return books.get(id);
    }
    public boolean update(Book bk){
        if(bk.getId()==null)
        {
            bk.setId(nextId++);
        }
        books.put(bk.getId(),bk);
        return true;
    }
    public boolean delete(Integer id){
        if(books.remove(id)==null)
            return false;
        else
            return true;
    }
    public Map<Integer,Book> getAll(){
        return books;
    }
}

Web Service資源層：

@Path("books")
public class Books {
    private final BookDao bookDao;
    public Books() {
        bookDao = new BookDao();
    }
    @GET
    @Produces({MediaType.APPLICATION_JSON})
    public Map<Integer,Book> getAllBooks(){
        return bookDao.getAll();
    }
    @Path("book")
    @GET
    @Produces({MediaType.APPLICATION_JSON})
    public Book getBook(@QueryParam("id")final int BookId){
        return bookDao.get(BookId);
    }

    @POST
    @Produces({MediaType.APPLICATION_JSON})
    public Boolean insertBook(final Book bk)
    {
        return bookDao.update(bk);
    }

    @PUT
    @Produces({MediaType.APPLICATION_JSON})
    public Boolean putBook(final Book bk){
        return bookDao.update(bk);
    }
    @DELETE
    @Produces({MediaType.APPLICATION_JSON})
    public Boolean delBook(@QueryParam(("id"))final Integer bookId){
        return bookDao.delete(bookId);
    }
}

執行後，可以通過application.wadl檢視提供的REST API及呼叫方法。另外，REST API可以採用RestClient測試。

在設計資源類時必須注意以下幾點：

1、資源類必須是public訪問型別

2、資源類的建構函式也是public訪問型別

3、專案檔案及程式碼採用UTF-8格式儲存，否則容易導致後面除錯的亂碼問題

4、用到JSON編碼，需要加入JackSON依賴包

5、實體類要提供無參建構函式，否則從相應的JSON字串無法解析出實體類