标签：json java spring jackson apache-camel
我有一个Java项目,它当前将一个映射返回给Camel而没有任何嵌套的键,值对,并且Jackson库使用Jackson库将它编组到JSON中.
例如,如果我将以下两个键值放入demoMap中：
Map<String,String> demoMap = new TreeMap<String,String>
demoMap.put("key1","5");
demoMap.put("key2","10");
我得到以下JSON：
{"key1":"5","key2":"10"}
但是,现在我的一些键值条目将具有可选的可见性,我需要将其作为嵌套键值放在我的地图中.任何没有可选可见性的键值都将使用默认值.所以,例如,如果我指定key1和key2的可见性,而不是key3,我希望得到JSON,如下所示：
{"key1":"5",
"key2":"10",
"key3":"17",
"visibility" : { "key1": "a&b&!c", "key2": "a&b", "_default": "a" }
}
如何让Camel使用嵌套键,值对来编组Java对象？我是一个视觉学习者,所以一个简单的例子会有所帮助.
我尝试更改我的Map以获得作为对象的值,即：
Map<String,Object> demoMap = new TreeMap<String,Object>
然后尝试使用http://examples.javacodegeeks.com/core-java/json/jackson/convert-java-map-to-from-json-using-jackson-example/添加嵌套键,一些键的值使用http://examples.javacodegeeks.com/core-java/json/jackson/convert-java-map-to-from-json-using-jackson-example/作为参考,但意识到这只是给了我一堆嵌套值在一个键下,而不是一堆嵌套键,值对.
即使我尝试使用grins,我也遇到了一个来自Camel处理器的错误,其中包含java.lang.ClassCastException,声明java.util.ArrayList无法转换为java.lang.String
同样,当我尝试在我的demoMap中嵌套Map时,我得到了这个ClassCastException：
3244 [hello.world.request.timer] ERROR org.apache.camel.processor.DefaultErrorHandler - Failed delivery for exchangeId: e6518e39-89b7-435e-96d9-ce26811ac67e. Exhausted after delivery attempt: 1 caught: java.lang.ClassCastException: java.util.HashMap cannot be cast to java.lang.String
所以我知道不怎么做. ： – /
我在http://camel.apache.org/json.html重新阅读了Camel JSON文档,但在撰写本文时,它没有使用嵌套键,值对指定示例.
更新：根据汤姆的反馈我创建了两个地图,即
Map<String,String> keyvalues = new TreeMap<String,String>();
Map<String,String> visibility = new TreeMap<String,String>();
这是我的类,我称之为SensorGenerator,它将属性文件加载到Map中：
package sample;
import java.util.Map;
import java.util.Properties;
import java.util.TreeMap;
import org.codehaus.jackson.annotate.JsonAnyGetter;
import org.codehaus.jackson.annotate.JsonProperty;
public class SensorGenerator {
private Properties sourceProperties;
// create a map of sensor keyvalues, and a map of sensor visibility
Map<String,String> keyvalues = new TreeMap<String,String>();
@JsonProperty
Map<String,String> visibility = new TreeMap<String,String>();
@JsonAnyGetter
public Map<String, String> getKeyvalues() {
for (Object key : sourceProperties.keySet()) {
// Separate out each of the field:datatype:visibility tuples as an entry in the
// values array
String[] values = sourceProperties.getProperty((String) key).split(
",");
// split the key between 'sensor' and the 'number' Ex: sensor1 -> sensor,1
String[] keyArray = key.toString().split("(?<=([a-zA-Z]++))");
String keyNumber = keyArray[1]; // grab the number to append for each sensor
// define string buffer that appends sensor number for each sensor's
// keys. Ex: sensor1 would have s1make, s1makeDataType, etc.
StringBuffer sensorNumberStringBuffer = new StringBuffer();
sensorNumberStringBuffer.append("s");
sensorNumberStringBuffer.append(keyNumber);
// make, its data type, and visibility (with s# prefix)
StringBuffer makeStringBuffer = new StringBuffer();
makeStringBuffer.append(sensorNumberStringBuffer);
makeStringBuffer.append("make");
StringBuffer makeDataTypeStringBuffer = new StringBuffer();
makeDataTypeStringBuffer.append(sensorNumberStringBuffer);
makeDataTypeStringBuffer.append("makeDataType");
StringBuffer makeVizStringBuffer = new StringBuffer();
makeVizStringBuffer.append(sensorNumberStringBuffer);
makeVizStringBuffer.append("makeViz");
// model, its data type, and visibility (with s# prefix)
StringBuffer modelStringBuffer = new StringBuffer();
modelStringBuffer.append(sensorNumberStringBuffer);
modelStringBuffer.append("model");
StringBuffer modelDataTypeStringBuffer = new StringBuffer();
modelDataTypeStringBuffer.append(sensorNumberStringBuffer);
modelDataTypeStringBuffer.append("modelDataType");
StringBuffer modelVizStringBuffer = new StringBuffer();
modelVizStringBuffer.append(sensorNumberStringBuffer);
modelVizStringBuffer.append("modelViz");
// serialNumber, its data type, and visibility (with s# prefix)
StringBuffer serialNumberStringBuffer = new StringBuffer();
serialNumberStringBuffer.append(sensorNumberStringBuffer);
serialNumberStringBuffer.append("serialNumber");
StringBuffer serialNumberDataTypeStringBuffer = new StringBuffer();
serialNumberDataTypeStringBuffer.append(sensorNumberStringBuffer);
serialNumberDataTypeStringBuffer.append("serialNumberDataType");
StringBuffer serialNumberVizStringBuffer = new StringBuffer();
serialNumberVizStringBuffer.append(sensorNumberStringBuffer);
serialNumberVizStringBuffer.append("serialNumberViz");
// sensorType, its data type, and visibility (with s# prefix)
StringBuffer sensorTypeStringBuffer = new StringBuffer();
sensorTypeStringBuffer.append(sensorNumberStringBuffer);
sensorTypeStringBuffer.append("sensorType");
StringBuffer sensorTypeDataTypeStringBuffer = new StringBuffer();
sensorTypeDataTypeStringBuffer.append(sensorNumberStringBuffer);
sensorTypeDataTypeStringBuffer.append("sensorTypeDataType");
StringBuffer sensorTypeVizStringBuffer = new StringBuffer();
sensorTypeVizStringBuffer.append(sensorNumberStringBuffer);
sensorTypeVizStringBuffer.append("sensorTypeViz");
// put all the field:datatype keyvalues for this sensor in the keyvalues map
// and visibilities in the visibility map
// make, data type, and visibility
keyvalues.put(makeStringBuffer.toString(), values[0].split(":")[0]);
keyvalues.put(makeDataTypeStringBuffer.toString(), values[0].split(":")[1]);
visibility.put(makeVizStringBuffer.toString(), values[0].split(":")[2]);
// model, data type, and visibility
keyvalues.put(modelStringBuffer.toString(), values[1].split(":")[0]);
keyvalues.put(modelDataTypeStringBuffer.toString(), values[1].split(":")[1]);
visibility.put(modelVizStringBuffer.toString(), values[1].split(":")[2]);
// serialNumber, data type, and visibility
keyvalues.put(serialNumberStringBuffer.toString(), values[2].split(":")[0]);
keyvalues.put(serialNumberDataTypeStringBuffer.toString(), values[2].split(":")[1]);
visibility.put(serialNumberVizStringBuffer.toString(), values[2].split(":")[2]);
// sensorType, data type, and visibility
keyvalues.put(sensorTypeStringBuffer.toString(), values[3].split(":")[0]);
keyvalues.put(sensorTypeDataTypeStringBuffer.toString(), values[3].split(":")[1]);
visibility.put(sensorTypeVizStringBuffer.toString(), values[3].split(":")[2]);
// add in default visibility
visibility.put("_default", "a");
}
return keyvalues;
}
public void setSourceProperties(Properties properties) {
this.sourceProperties = properties;
}
}
现在我只是将默认可见性硬编码为“a”,但稍后会将其更改为也从属性文件中提取.
解决方法:
您的结构不仅仅是一张地图.这是两个不同序列化的地图.表示这一点的一种方法是：
public class Whatever{
Map<String,String> keyvalues;
Map<String,String> visibility;
}
你最终得到的是这个,虽然代表数据远非理想：
{
"keyvalues" : { "key1": "5", "key2": "10", "key3": "17"},
"visibility" : { "key1": "a&b&!c", "key2": "a&b", "_default": "a" }
}
要获得所需内容,请使用@JsonAnyGetter.像这样的东西(它可以更容易使用)：
public class Whatever{
Map<String,String> keyvalues = new TreeMap<String,String>();
@JsonProperty
Map<String,String> visibility = new TreeMap<String,String>();
@JsonAnyGetter
public Map<String, String> getKeyvalues() {
return keyvalues;
}
}
产生：
{"visibility":{"key1":"a&b&!c","key2":"a&b"},"key1":"5","key2":"10"}
我今天一直在与这个斗争,你的问题激励我让它变成血腥的工作：D注释在这里：https://github.com/FasterXML/jackson-annotations/wiki/Jackson-Annotations
请参见此处的JUnit测试：https://gist.github.com/TomDemeranville/7009250
标签：json,java,spring,jackson,apache-camel 来源： https://codeday.me/bug/20190517/1121247.html
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