修改Json#node方法，改为返回List<Json>，方便链式调用

webmagic-core/src/main/java/us/codecraft/webmagic/selector/Json.java

@@ -3,6 +3,7 @@ package us.codecraft.webmagic.selector;
 import com.alibaba.fastjson.JSON;
 import us.codecraft.xsoup.XTokenQueue;
 
+import java.util.ArrayList;
 import java.util.List;
 
 /**
@@ -52,6 +53,20 @@ public class Json extends PlainText {
     @Override
     public Selectable jsonPath(String jsonPath) {
         JsonPathSelector jsonPathSelector = new JsonPathSelector(jsonPath);
-        return selectList(jsonPathSelector,getSourceTexts());
+        List<String> results = new ArrayList<String>();
+        for (String string : getSourceTexts()) {
+            List<String> result = jsonPathSelector.selectList(string);
+            results.addAll(result);
+        }
+        return new Json(results);
+    }
+
+    @Override
+    public List<Selectable> nodes() {
+        List<Selectable> nodes = new ArrayList<Selectable>(getSourceTexts().size());
+        for (String string : getSourceTexts()) {
+            nodes.add(new Json(string));
+        }
+        return nodes;
     }
 }

webmagic-core/src/test/java/us/codecraft/webmagic/selector/JsonTest.java

@@ -14,6 +14,8 @@ public class JsonTest {
 
     private String textWithBrackerInContent = "callback({\"name\":\"json)\"})";
 
+    private String textChained = "callback({\"provinces\": [{cities: [{\"name\": \"shanghai\"}]}]})";
+
     @Test
     public void testRemovePadding() throws Exception {
         String name = new Json(text).removePadding("callback").jsonPath("$.name").get();
@@ -25,4 +27,11 @@ public class JsonTest {
         String name = new Json(textWithBrackerInContent).removePadding("callback").jsonPath("$.name").get();
         assertThat(name).isEqualTo("json)");
     }
+
+    @Test
+    public void testChainCall() throws Exception {
+        String shanghai = new Json(textChained).removePadding("callback").jsonPath("$.provinces").nodes().get(0)
+                                                    .jsonPath("$.cities").nodes().get(0).jsonPath("$.name").get();
+        assertThat(shanghai).isEqualTo("shanghai");
+    }
 }