Struts2插件 —— struts2-json-plugin-2.x.x

为了方便AJAX与服务器进行数据交换，struts2中加入的json插件可用于对象的序列化和反序列化。

相关JAR包

struts2-json-plugin.2.x.x.jar

修改Struts2配置文件

更改package元素的extends属性

<package name="default" extends="json-default">

配置result元素的type属性为json，将把Action中属性序列化返回

<result type="json" /> 

如果需要处理以JSON文本提交的请求，可在action元素中添加子元素interceptor引用JSON插件包中声明的拦截器：json。

<interceptor-ref name="json" />

result type参数

result type对应的类为：org.apache.struts2.json.JSONInterceptor。下面是一些常用的result param：

root	<paramname="root">person</param>
excludeNullProperties	是否去掉值为null的属性， 默认值为false。 <paramname="excludeNullProperties">true</param>
ignoreHierarchy	是否忽略继承关系，ignoreHierarchy值默认为true。设置为false后，父类的属性也将被构建在JSON字符串中。 <paramname="ignoreHierarchy">false</param>
includeProperties	响应结果需要包含的属性值，支持正则表达式，可用","分隔以使用多个正则表达式匹配。 <paramname="includeProperties">person.*, person\.name</param>
excludeProperties	响应结果需要排除的属性值，支持正则表达式，可用“,”分隔以使用多个正则表达式匹配。

JSONInterceptor源码：

/**
* Populates an action from a JSON string
*/
public class JSONInterceptor extends AbstractInterceptor {
private static final long serialVersionUID = 4950170304212158803L;
private static final Logger LOG = LoggerFactory.getLogger(JSONInterceptor.class);
private boolean enableSMD = false;
private boolean enableGZIP = false;
private boolean wrapWithComments;
private boolean prefix;
private String defaultEncoding = "ISO-8859-1";
private boolean ignoreHierarchy = true;
private String root;
private List<Pattern> excludeProperties;
private List<Pattern> includeProperties;
private boolean ignoreSMDMethodInterfaces = true;
private JSONPopulator populator = new JSONPopulator();
private JSONCleaner dataCleaner = null;
private boolean debug = false;
private boolean noCache = false;
private boolean excludeNullProperties;
private String callbackParameter;
private String contentType;

@SuppressWarnings("unchecked")
public String intercept(ActionInvocation invocation) throws Exception {
HttpServletRequest request = ServletActionContext.getRequest();
HttpServletResponse response = ServletActionContext.getResponse();
String contentType = request.getHeader("content-type");
if (contentType != null) {
int iSemicolonIdx;
if ((iSemicolonIdx = contentType.indexOf(";")) != -1)
contentType = contentType.substring(0, iSemicolonIdx);
}

Object rootObject = null;
if (this.root != null) {
ValueStack stack = invocation.getStack();
rootObject = stack.findValue(this.root);

if (rootObject == null) {
throw new RuntimeException("Invalid root expression: '" + this.root + "'.");
}
}

if ((contentType != null) && contentType.equalsIgnoreCase("application/json")) {
// load JSON object
Object obj = JSONUtil.deserialize(request.getReader());

if (obj instanceof Map) {
Map json = (Map) obj;

// clean up the values
if (dataCleaner != null)
dataCleaner.clean("", json);

if (rootObject == null) // model overrides action
rootObject = invocation.getStack().peek();

// populate fields
populator.populateObject(rootObject, json);
} else {
LOG.error("Unable to deserialize JSON object from request");
throw new JSONException("Unable to deserialize JSON object from request");
}
} else if ((contentType != null) && contentType.equalsIgnoreCase("application/json-rpc")) {
Object result;
if (this.enableSMD) {
// load JSON object
Object obj = JSONUtil.deserialize(request.getReader());

if (obj instanceof Map) {
Map smd = (Map) obj;

if (rootObject == null) // model makes no sense when using RPC
rootObject = invocation.getAction();

// invoke method
try {
result = this.invoke(rootObject, smd);
} catch (Exception e) {
RPCResponse rpcResponse = new RPCResponse();
rpcResponse.setId(smd.get("id").toString());
rpcResponse.setError(new RPCError(e, RPCErrorCode.EXCEPTION, getDebug()));

result = rpcResponse;
}
} else {
String message = "SMD request was not in the right format. See http://json-rpc.org"; 
RPCResponse rpcResponse = new RPCResponse();
rpcResponse.setError(new RPCError(message, RPCErrorCode.INVALID_PROCEDURE_CALL));
result = rpcResponse;
}
} else {
String message = "Request with content type of 'application/json-rpc' was received but SMD is "
+ "not enabled for this interceptor. Set 'enableSMD' to true to enable it";

RPCResponse rpcResponse = new RPCResponse();
rpcResponse.setError(new RPCError(message, RPCErrorCode.SMD_DISABLED));
result = rpcResponse;
}

String json = JSONUtil.serialize(result, excludeProperties, getIncludeProperties(),
ignoreHierarchy, excludeNullProperties);
json = addCallbackIfApplicable(request, json);
boolean writeGzip = enableGZIP && JSONUtil.isGzipInRequest(request);
JSONUtil.writeJSONToResponse(new SerializationParams(response, this.defaultEncoding,
this.wrapWithComments, json, true, writeGzip, noCache, -1, -1, prefix, "application/json"));

return Action.NONE;
} else {
if (LOG.isDebugEnabled()) {
LOG.debug("Content type must be 'application/json' or 'application/json-rpc'. " +
"Ignoring request with content type " + contentType);
}
}

return invocation.invoke();
}

@SuppressWarnings("unchecked")
public RPCResponse invoke(Object object, Map data) throws IllegalArgumentException,
IllegalAccessException, InvocationTargetException, JSONException, InstantiationException,
NoSuchMethodException, IntrospectionException {

RPCResponse response = new RPCResponse();

// validate id
Object id = data.get("id");
if (id == null) {
String message = "'id' is required for JSON RPC";
response.setError(new RPCError(message, RPCErrorCode.METHOD_NOT_FOUND));
return response;
}
// could be a numeric value
response.setId(id.toString());

// the map is going to have: 'params', 'method' and 'id' (for the
// client to identify the response)
Class clazz = object.getClass();

// parameters
List parameters = (List) data.get("params");
int parameterCount = parameters != null ? parameters.size() : 0;

// method
String methodName = (String) data.get("method");
if (methodName == null) {
String message = "'method' is required for JSON RPC";
response.setError(new RPCError(message, RPCErrorCode.MISSING_METHOD));
return response;
}

Method method = this.getMethod(clazz, methodName, parameterCount);
if (method == null) {
String message = "Method " + methodName + " could not be found in action class.";
response.setError(new RPCError(message, RPCErrorCode.METHOD_NOT_FOUND));
return response;
}

// parameters
if (parameterCount > 0) {
Class[] parameterTypes = method.getParameterTypes();
Type[] genericTypes = method.getGenericParameterTypes();
List invocationParameters = new ArrayList();

// validate size
if (parameterTypes.length != parameterCount) {
// size mismatch
String message = "Parameter count in request, " + parameterCount
+ " do not match expected parameter count for " + methodName + ", "
+ parameterTypes.length;

response.setError(new RPCError(message, RPCErrorCode.PARAMETERS_MISMATCH));
return response;
}

// convert parameters
for (int i = 0; i < parameters.size(); i++) {
Object parameter = parameters.get(i);
Class paramType = parameterTypes[i];
Type genericType = genericTypes[i];

// clean up the values
if (dataCleaner != null)
parameter = dataCleaner.clean("[" + i + "]", parameter);

Object converted = populator.convert(paramType, genericType, parameter, method);
invocationParameters.add(converted);
}

response.setResult(method.invoke(object, invocationParameters.toArray()));
} else {
response.setResult(method.invoke(object, new Object[0]));
}

return response;
}

@SuppressWarnings("unchecked")
private Method getMethod(Class clazz, String name, int parameterCount) {
Method[] smdMethods = JSONUtil.listSMDMethods(clazz, ignoreSMDMethodInterfaces);

for (Method method : smdMethods) {
if (checkSMDMethodSignature(method, name, parameterCount)) {
return method;
}
}
return null;
}

/**
* Look for a method in clazz carrying the SMDMethod annotation with
* matching name and parametersCount
*
* @return true if matches name and parameterCount
*/
private boolean checkSMDMethodSignature(Method method, String name, int parameterCount) {

SMDMethod smdMethodAnntotation = method.getAnnotation(SMDMethod.class);
if (smdMethodAnntotation != null) {
String alias = smdMethodAnntotation.name();
boolean paramsMatch = method.getParameterTypes().length == parameterCount;
if (((alias.length() == 0) && method.getName().equals(name) && paramsMatch)
|| (alias.equals(name) && paramsMatch)) {
return true;
}
}

return false;
}

protected String addCallbackIfApplicable(HttpServletRequest request, String json) {
if ((callbackParameter != null) && (callbackParameter.length() > 0)) {
String callbackName = request.getParameter(callbackParameter);
if ((callbackName != null) && (callbackName.length() > 0))
json = callbackName + "(" + json + ")";
}
return json;
}

public boolean isEnableSMD() {
return this.enableSMD;
}

public void setEnableSMD(boolean enableSMD) {
this.enableSMD = enableSMD;
}

/**
* Ignore annotations on methods in interfaces You may need to set to this
* true if your action is a proxy/enhanced as annotations are not inherited
*/
public void setIgnoreSMDMethodInterfaces(boolean ignoreSMDMethodInterfaces) {
this.ignoreSMDMethodInterfaces = ignoreSMDMethodInterfaces;
}

/**
* Wrap generated JSON with comments. Only used if SMD is enabled.
*
* @param wrapWithComments
*/
public void setWrapWithComments(boolean wrapWithComments) {
this.wrapWithComments = wrapWithComments;
}

@Inject(StrutsConstants.STRUTS_I18N_ENCODING)
public void setDefaultEncoding(String val) {
this.defaultEncoding = val;
}

/**
* Ignore properties defined on base classes of the root object.
*
* @param ignoreHierarchy
*/
public void setIgnoreHierarchy(boolean ignoreHierarchy) {
this.ignoreHierarchy = ignoreHierarchy;
}

/**
* Sets the root object to be deserialized, defaults to the Action
*
* @param root
*            OGNL expression of root object to be serialized
*/
public void setRoot(String root) {
this.root = root;
}

/**
* Sets the JSONPopulator to be used
*
* @param populator
*            JSONPopulator
*/
public void setJSONPopulator(JSONPopulator populator) {
this.populator = populator;
}

/**
* Sets the JSONCleaner to be used
*
* @param dataCleaner
*            JSONCleaner
*/
public void setJSONCleaner(JSONCleaner dataCleaner) {
this.dataCleaner = dataCleaner;
}

/**
* @return true if debugging is turned on
*/
public boolean getDebug() {
Boolean devModeOverride = FilterDispatcher.getDevModeOverride();
return devModeOverride != null ? devModeOverride.booleanValue() : this.debug;
}

/**
* Turns debugging on or off
*
* @param debug
*            true or false
*/
public void setDebug(boolean debug) {
this.debug = debug;
}

@Inject(StrutsConstants.STRUTS_DEVMODE)
public void setDevMode(
String mode)
{
setDebug("true".equalsIgnoreCase(mode));
}

/**
* Sets a comma-delimited list of regular expressions to match properties
* that should be excluded from the JSON output.
*
* @param commaDelim
*            A comma-delimited list of regular expressions
*/
public void setExcludeProperties(String commaDelim) {
Set<String> excludePatterns = JSONUtil.asSet(commaDelim);
if (excludePatterns != null) {
this.excludeProperties = new ArrayList<Pattern>(excludePatterns.size());
for (String pattern : excludePatterns) {
this.excludeProperties.add(Pattern.compile(pattern));
}
}
}

/**
* Sets a comma-delimited list of wildcard expressions to match
* properties that should be excluded from the JSON output.
*
* @param commaDelim
*            A comma-delimited list of wildcard expressions
*/
public void setExcludeWildcards(String commaDelim) {
Set<String> excludePatterns = JSONUtil.asSet(commaDelim);
if (excludePatterns != null) {
this.excludeProperties = new ArrayList<Pattern>(excludePatterns.size());
for (String pattern : excludePatterns) {
this.excludeProperties.add(WildcardUtil.compileWildcardPattern(pattern));
}
}
}

/**
* Sets a comma-delimited list of regular expressions to match properties
* that should be included from the JSON output.
*
* @param commaDelim
*            A comma-delimited list of regular expressions
*/
public void setIncludeProperties(String commaDelim) {
includeProperties = JSONUtil.processIncludePatterns(JSONUtil.asSet(commaDelim), JSONUtil.REGEXP_PATTERN);
}

/**
* Sets a comma-delimited list of wildcard expressions to match
* properties that should be included from the JSON output.  The
* standard boilerplate (id, error, debug) are automatically included,
* as appropriate, so you only need to provide patterns for the
* contents of "result".
*
* @param commaDelim
*            A comma-delimited list of wildcard expressions
*/
public void setIncludeWildcards(String commaDelim) {
includeProperties = JSONUtil.processIncludePatterns(JSONUtil.asSet(commaDelim), JSONUtil.WILDCARD_PATTERN);
if (includeProperties != null) {
includeProperties.add(Pattern.compile("id"));
includeProperties.add(Pattern.compile("result"));
includeProperties.add(Pattern.compile("error"));
includeProperties.add(WildcardUtil.compileWildcardPattern("error.code"));
}
}

/**
* Returns the appropriate set of includes, based on debug setting.
* Derived classes can override if there are additional, custom
* debug-only parameters.
*/
protected List getIncludeProperties() {
if (includeProperties != null && getDebug()) {
List<Pattern> list = new ArrayList<Pattern>(includeProperties);
list.add(Pattern.compile("debug"));
list.add(WildcardUtil.compileWildcardPattern("error.*"));
return list;
} else {
return includeProperties;
}
}

public boolean isEnableGZIP() {
return enableGZIP;
}

/**
* Setting this property to "true" will compress the output.
*
* @param enableGZIP
*            Enable compressed output
*/
public void setEnableGZIP(boolean enableGZIP) {
this.enableGZIP = enableGZIP;
}

public boolean isNoCache() {
return noCache;
}

/**
* Add headers to response to prevent the browser from caching the response
*
* @param noCache
*/
public void setNoCache(boolean noCache) {
this.noCache = noCache;
}

public boolean isExcludeNullProperties() {
return excludeNullProperties;
}

/**
* Do not serialize properties with a null value
*
* @param excludeNullProperties
*/
public void setExcludeNullProperties(boolean excludeNullProperties) {
this.excludeNullProperties = excludeNullProperties;
}

public void setCallbackParameter(String callbackParameter) {
this.callbackParameter = callbackParameter;
}

public String getCallbackParameter() {
return callbackParameter;
}

/**
* Add "{} && " to generated JSON
*
* @param prefix
*/
public void setPrefix(boolean prefix) {
this.prefix = prefix;
}

public void setContentType(String contentType) {
this.contentType = contentType;
}
}