ㄘㄊ的根莖類成長記錄: 使用Eclipse Luna + Tomcat 7 + Jersey 2架設RESTful service

前言

此篇文章介紹如何使用Jersey架設RESTful web service，使用到的工具如下
1. Eclipse Luna
2. Tomcat 7
3. Jersey 2.11

為避免對Maven或Gradle不熟悉的人感到疑惑，因此此篇文章只針對如何使用Jersey 2架設RESTful service，不使用Maven或Gradle進行管理

架設步驟

1. 開啟Eclipse

2. 建立新的專案File -> New -> Dynamic Web Project

3. 輸入專案名稱JerseySample並選擇Apache Tomcat v7.0作為Target runtime，記得要把Generate web.xml deployment descriptor打勾

4. 將jersey官網下載的jaxrs-ri-2.11.zip解壓縮，接著把所有的jar檔複製到jerseySample/WebContent/WEB-INF/lib下

5. 重新整理JerseySample專案確保lib都有正常載入

6. 修改web.xml讓Tomcat可以正確載入Jersey相關資源

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
  <display-name>JerseySample</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  
  <servlet>
    <servlet-name>Jersey Web Application</servlet-name>
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>
    <init-param>
      <param-name>jersey.config.server.provider.packages</param-name>
      <param-value>org.sample.test</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
  </servlet>
  <servlet-mapping>
    <servlet-name>Jersey Web Application</servlet-name>
    <url-pattern>/api/*</url-pattern>
  </servlet-mapping> 
  
</web-app>

參數說明
i. servlet-class
Jersey 1的servlet-class為
com.sun.jersey.spi.container.servlet.ServletContainer

而Jersey 2的servlet-class必須改成(畢竟Sun已經R.I.P.了QAQ........)
org.glassfish.jersey.servlet.ServletContainer

ii. jersey.config.server.provider.packages
Jersey掃描的packet路徑，resource的java檔要放在此package下

iii. url-pattern
Resource對應的URL位置，client端必須要照此參數設定才能呼叫到對應的resource

7. 建立package: org.sample.test

8. 建立resource的java檔案: Hello.java

9. 加入以下的程式碼至Hello.java

package test;
import javax.ws.rs.GET;
import javax.ws.rs.Path;
import javax.ws.rs.Produces;
import javax.ws.rs.core.MediaType;

@Path("/hello")
public class Hello {
    // This method is called if TEXT_PLAIN is request
    @GET
    @Produces(MediaType.TEXT_PLAIN)
    public String sayPlainTextHello() {
        return "Hello Jersey";
    }

    // This method is called if XML is request
    @GET
    @Produces(MediaType.TEXT_XML)
    public String sayXMLHello() {
        return "" + " Hello Jersey" + "";
    }

    // This method is called if HTML is request
    @GET
    @Produces(MediaType.TEXT_HTML)
    public String sayHtmlHello() {
        return "<html> " + "<title>" + "Hello Jersey" + "</title>"
              + "<body><h1>" 
              + "Hello Jersey"
              + "</h1></body></html></pre>" 
              + " ";
 }
}

10. 將專案在Tomcat上跑起來，並使用瀏覽器檢查http://localhost:8080/JerseySample/api/hello是否正確