java中使用XStream實作将對象轉為xml格式字元串或者将xml格式的字元串轉換為對象

我們經常會有需求，比如調用别人的接口，别人會傳回給你json或者xml格式的資料，然後我們要轉換為相應的對象供我們自己使用；

也有的時候是别人的調我們的接口，讓我們提供xml格式的資料或者json格式的資料，json的話這裡都不說了，很好處理，甚至springMvc本身就很容易支援。

下面隻介紹xml和對象彼此轉換

首先我們需要引入的jar包：xstream-1.4.8.jar

下面直接貼代碼，代碼是在springMvc環境下寫的

<code class="language-java hljs  has-numbering"><span class="hljs-annotation">@Controller</span>
<span class="hljs-keyword">public</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">NavigationAppDataController</span> <span class="hljs-keyword">extends</span> <span class="hljs-title">BaseController</span>{</span>

    <span class="hljs-annotation">@SuppressWarnings</span>(<span class="hljs-string">"unused"</span>)
    <span class="hljs-keyword">private</span> <span class="hljs-keyword">static</span> <span class="hljs-keyword">final</span> Logger     log = LoggerFactory.getLogger(NavigationAppDataController.class);

    <span class="hljs-annotation">@Autowired</span>
    <span class="hljs-keyword">private</span> StoNavigationAppManager stoNavigationAppManager;

    <span class="hljs-annotation">@RequestMapping</span>(value = <span class="hljs-string">"/appsite/getNavigationXmlData.htm"</span>)
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">getNavigationXmlData</span>(HttpServletRequest request,HttpServletResponse response){
        List<NavigationAppCommand> findStoreNavigationAppToXml = stoNavigationAppManager.findStoreNavigationAppData();
        XStreamConfig xStreamConfig = <span class="hljs-keyword">new</span> XStreamConfig();
        <span class="hljs-comment">// 這裡是什麼意思我下面文字中會介紹，大概就是對xml中節點進行重命名的</span>
        xStreamConfig.getAliasMap().put(<span class="hljs-string">"topcategories"</span>, List.class);
        xStreamConfig.getAliasMap().put(<span class="hljs-string">"category"</span>, NavigationAppCommand.class);
        String xml = toXML(findStoreNavigationAppToXml, xStreamConfig);
        <span class="hljs-comment">// 設定傳回資料的編碼格式</span>
        response.setCharacterEncoding(CharsetType.UTF8);
        <span class="hljs-comment">// 設定内容類型，決定浏覽器将以什麼類型讀我們傳回的資料進行展示</span>
        response.setContentType(<span class="hljs-string">"application/xml"</span>);
        <span class="hljs-comment">// 将資料寫入response傳回給請求端</span>
        response.getWriter().write(xml);
    }

    <span class="hljs-javadoc">/**
     * 将bean對象根據xStreamConfig格式轉成xml格式的字元串傳回
     * 
     *<span class="hljs-javadoctag"> @param</span> bean
     *            對象
     *<span class="hljs-javadoctag"> @param</span> xStreamConfig
     *            配置
     *<span class="hljs-javadoctag"> @return</span>
     */</span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> String <span class="hljs-title">toXML</span>(Object bean,XStreamConfig xStreamConfig){
        XStream xstream = constructXStream(xStreamConfig);
        <span class="hljs-keyword">return</span> xstream.toXML(bean);
    }

    <span class="hljs-javadoc">/**
     * 将xml字元串轉為相對應的對象
     * 
     *<span class="hljs-javadoctag"> @param</span> xml
     *<span class="hljs-javadoctag"> @return</span>
     */</span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <T> T <span class="hljs-title">fromXML</span>(String xml){
        <span class="hljs-keyword">return</span> fromXML(xml, <span class="hljs-keyword">null</span>);
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> <T> T <span class="hljs-title">fromXML</span>(String xml,XStreamConfig xStreamConfig){
        XStream xstream = constructXStream(xStreamConfig);
        <span class="hljs-keyword">return</span> (T) xstream.fromXML(xml);
    }

    <span class="hljs-keyword">public</span> <span class="hljs-keyword">static</span> XStream <span class="hljs-title">constructXStream</span>(XStreamConfig xStreamConfig){
        XStream xstream = <span class="hljs-keyword">new</span> XStream();

        <span class="hljs-keyword">if</span> (Validator.isNotNullOrEmpty(xStreamConfig)){

            <span class="hljs-comment">// *******************alias********************************************</span>
            Map<String, Class<?>> aliasMap = xStreamConfig.getAliasMap();
            <span class="hljs-keyword">if</span> (Validator.isNotNullOrEmpty(aliasMap)){
                <span class="hljs-keyword">for</span> (Map.Entry<String, Class<?>> entry : aliasMap.entrySet()){
                    String key = entry.getKey();
                    Class<?> value = entry.getValue();
                    <span class="hljs-comment">// 類重命名</span>
                    xstream.alias(key, value);
                }
            }
            <span class="hljs-comment">// *******************implicitCollectionMap********************************************</span>
            Map<String, Class<?>> implicitCollectionMap = xStreamConfig.getImplicitCollectionMap();
            <span class="hljs-keyword">if</span> (Validator.isNotNullOrEmpty(implicitCollectionMap)){
                <span class="hljs-keyword">for</span> (Map.Entry<String, Class<?>> entry : implicitCollectionMap.entrySet()){
                    String key = entry.getKey();
                    Class<?> value = entry.getValue();
                    xstream.addImplicitCollection(value, key);
                }
            }
        }
    }
}</code><ul style="display: block;" class="pre-numbering"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li><li>42</li><li>43</li><li>44</li><li>45</li><li>46</li><li>47</li><li>48</li><li>49</li><li>50</li><li>51</li><li>52</li><li>53</li><li>54</li><li>55</li><li>56</li><li>57</li><li>58</li><li>59</li><li>60</li><li>61</li><li>62</li><li>63</li><li>64</li><li>65</li><li>66</li><li>67</li><li>68</li><li>69</li><li>70</li><li>71</li><li>72</li><li>73</li><li>74</li><li>75</li><li>76</li><li>77</li><li>78</li><li>79</li><li>80</li><li>81</li></ul>      

<code class="language-java hljs  has-numbering"><span class="hljs-javadoc">/**
 * XStream相關配置.
 *
 */</span>
<span class="hljs-keyword">public</span> <span class="hljs-keyword">final</span> <span class="hljs-class"><span class="hljs-keyword">class</span> <span class="hljs-title">XStreamConfig</span>{</span>

    <span class="hljs-javadoc">/** 别名. */</span>
    <span class="hljs-keyword">private</span> Map<String, Class<?>> aliasMap              = <span class="hljs-keyword">new</span> HashMap<String, Class<?>>();

    <span class="hljs-javadoc">/** 隐式集合 隐藏,隐藏,比如下面有list,泛型中的第二個參數 Class 是 ownerType. */</span>
    <span class="hljs-keyword">private</span> Map<String, Class<?>> implicitCollectionMap = <span class="hljs-keyword">new</span> HashMap<String, Class<?>>();

    <span class="hljs-javadoc">/**
     * 獲得 别名.
     *
     *<span class="hljs-javadoctag"> @return</span> the aliasMap
     */</span>
    <span class="hljs-keyword">public</span> Map<String, Class<?>> <span class="hljs-title">getAliasMap</span>(){
        <span class="hljs-keyword">return</span> aliasMap;
    }

    <span class="hljs-javadoc">/**
     * 設定 别名.
     *
     *<span class="hljs-javadoctag"> @param</span> aliasMap
     *            the aliasMap to set
     */</span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setAliasMap</span>(Map<String, Class<?>> aliasMap){
        <span class="hljs-keyword">this</span>.aliasMap = aliasMap;
    }

    <span class="hljs-javadoc">/**
     * 獲得 隐式集合 隐藏,隐藏,比如下面有list,泛型中的第二個參數 Class 是 ownerType.
     *
     *<span class="hljs-javadoctag"> @return</span> the implicitCollectionMap
     */</span>
    <span class="hljs-keyword">public</span> Map<String, Class<?>> <span class="hljs-title">getImplicitCollectionMap</span>(){
        <span class="hljs-keyword">return</span> implicitCollectionMap;
    }

    <span class="hljs-javadoc">/**
     * 設定 隐式集合 隐藏,隐藏,比如下面有list,泛型中的第二個參數 Class 是 ownerType.
     *
     *<span class="hljs-javadoctag"> @param</span> implicitCollectionMap
     *            the implicitCollectionMap to set
     */</span>
    <span class="hljs-keyword">public</span> <span class="hljs-keyword">void</span> <span class="hljs-title">setImplicitCollectionMap</span>(Map<String, Class<?>> implicitCollectionMap){
        <span class="hljs-keyword">this</span>.implicitCollectionMap = implicitCollectionMap;
    }
}</code><ul style="display: block;" class="pre-numbering"><li>1</li><li>2</li><li>3</li><li>4</li><li>5</li><li>6</li><li>7</li><li>8</li><li>9</li><li>10</li><li>11</li><li>12</li><li>13</li><li>14</li><li>15</li><li>16</li><li>17</li><li>18</li><li>19</li><li>20</li><li>21</li><li>22</li><li>23</li><li>24</li><li>25</li><li>26</li><li>27</li><li>28</li><li>29</li><li>30</li><li>31</li><li>32</li><li>33</li><li>34</li><li>35</li><li>36</li><li>37</li><li>38</li><li>39</li><li>40</li><li>41</li><li>42</li><li>43</li><li>44</li><li>45</li><li>46</li><li>47</li><li>48</li><li>49</li><li>50</li></ul>      

實作方法很簡單另外這裡說一下response的幾個參數設定的意思。

1. response.setCharacterEncoding(CharsetType.UTF8);

   設定傳回資料的編碼格式如果不設定這個，傳回到客戶請求端的資料可能會亂碼，這個編碼格式一定要統一掉

2. response.setContentType(“application/xml”);

   設定内容類型，決定浏覽器将以什麼類型讀我們傳回的資料進行展示，如果不設定，那麼浏覽器顯示的就是一大坨xml格式的字元串，沒有任何效果，而設定之後就可以像我上面截圖的那樣，節點可以點選展開和關閉，并且資料和節點顔色對比明顯，便于觀看。