配置SpringMVC使用fastjson

MappingFastjson2JsonView.java

/**
 * Spring MVC {@link View} that renders JSON content by serializing the model for the current request
 * using fastjson.
 *
 * <p>By default, the entire contents of the model map (with the exception of framework-specific classes)
 * will be encoded as JSON. If the model contains only one key, you can have it extracted encoded as JSON
 * alone via  {@link #setExtractValueFromSingleKeyModel}.
 *
 * @author yanganyu
 * @date 2018/10/15 15:48
 */
public class MappingFastjson2JsonView extends AbstractView {
	/**
	 * Default content type: "application/json".
	 * Overridable through {@link #setContentType}.
	 */
	public static final String DEFAULT_CONTENT_TYPE = "application/json";

	private JsonEncoding encoding = JsonEncoding.UTF8;

	private boolean disableCaching = true;

	/**
	 * Default content type for JSONP: "application/javascript".
	 *
	 * @deprecated Will be removed as of Spring Framework 5.1, use
	 * <a href="https://docs.spring.io/spring/docs/5.0.x/spring-framework-reference/web.html#mvc-cors">CORS</a> instead.
	 */
	@Deprecated
	public static final String DEFAULT_JSONP_CONTENT_TYPE = "application/javascript";

	/**
	 * Pattern for validating jsonp callback parameter values.
	 */
	private static final Pattern CALLBACK_PARAM_PATTERN = Pattern.compile("[0-9A-Za-z_\\.]*");

	@Nullable
	private Set<String> modelKeys;

	private boolean extractValueFromSingleKeyModel = false;

	@Nullable
	private Set<String> jsonpParameterNames = new LinkedHashSet<>();

	public MappingFastjson2JsonView() {
		setContentType(DEFAULT_CONTENT_TYPE);
		setExposePathVariables(false);
	}

	/**
	 * Set the {@code JsonEncoding} for this view.
	 * By default, {@linkplain JsonEncoding#UTF8 UTF-8} is used.
	 */
	public void setEncoding(JsonEncoding encoding) {
		Assert.notNull(encoding, "'encoding' must not be null");
		this.encoding = encoding;
	}

	/**
	 * Return the {@code JsonEncoding} for this view.
	 */
	public final JsonEncoding getEncoding() {
		return this.encoding;
	}

	/**
	 * Disables caching of the generated JSON.
	 * <p>Default is {@code true}, which will prevent the client from caching the generated JSON.
	 */
	public void setDisableCaching(boolean disableCaching) {
		this.disableCaching = disableCaching;
	}

	/**
	 * Set whether to serialize models containing a single attribute as a map or
	 * whether to extract the single value from the model and serialize it directly.
	 * <p>The effect of setting this flag is similar to using
	 * {@code MappingJackson2HttpMessageConverter} with an {@code @ResponseBody}
	 * request-handling method.
	 * <p>Default is {@code false}.
	 */
	public void setExtractValueFromSingleKeyModel(boolean extractValueFromSingleKeyModel) {
		this.extractValueFromSingleKeyModel = extractValueFromSingleKeyModel;
	}

	@Override
	protected void prepareResponse(HttpServletRequest request, HttpServletResponse response) {
		setResponseContentType(request, response);
		response.setCharacterEncoding(this.encoding.getJavaName());
		if (this.disableCaching) {
			response.addHeader("Pragma", "no-cache");
			response.addHeader("Cache-Control", "no-cache, no-store, max-age=0");
			response.addDateHeader("Expires", 1L);
		}
	}

	/**
	 * {@inheritDoc}
	 */
	public void setModelKey(String modelKey) {
		this.modelKeys = Collections.singleton(modelKey);
	}

	/**
	 * Set the attributes in the model that should be rendered by this view.
	 * When set, all other model attributes will be ignored.
	 */
	public void setModelKeys(@Nullable Set<String> modelKeys) {
		this.modelKeys = modelKeys;
	}

	/**
	 * Return the attributes in the model that should be rendered by this view.
	 */
	@Nullable
	public final Set<String> getModelKeys() {
		return this.modelKeys;
	}

	/**
	 * Set JSONP request parameter names. Each time a request has one of those
	 * parameters, the resulting JSON will be wrapped into a function named as
	 * specified by the JSONP request parameter value.
	 * <p>As of Spring Framework 5.0.7, there is no parameter name configured
	 * by default.
	 *
	 * @see <a href="http://en.wikipedia.org/wiki/JSONP">JSONP Wikipedia article</a>
	 * @since 4.1
	 * @deprecated Will be removed as of Spring Framework 5.1, use
	 * <a href="https://docs.spring.io/spring/docs/5.0.x/spring-framework-reference/web.html#mvc-cors">CORS</a> instead.
	 */
	@Deprecated
	public void setJsonpParameterNames(Set<String> jsonpParameterNames) {
		this.jsonpParameterNames = jsonpParameterNames;
	}

	@Nullable
	private String getJsonpParameterValue(HttpServletRequest request) {
		if (this.jsonpParameterNames != null) {
			for (String name : this.jsonpParameterNames) {
				String value = request.getParameter(name);
				if (StringUtils.isEmpty(value)) {
					continue;
				}
				if (!isValidJsonpQueryParam(value)) {
					if (logger.isDebugEnabled()) {
						logger.debug("Ignoring invalid jsonp parameter value: " + value);
					}
					continue;
				}
				return value;
			}
		}
		return null;
	}

	/**
	 * Validate the jsonp query parameter value. The default implementation
	 * returns true if it consists of digits, letters, or "_" and ".".
	 * Invalid parameter values are ignored.
	 *
	 * @param value the query param value, never {@code null}
	 * @since 4.1.8
	 * @deprecated Will be removed as of Spring Framework 5.1, use
	 * <a href="https://docs.spring.io/spring/docs/5.0.x/spring-framework-reference/web.html#mvc-cors">CORS</a> instead.
	 */
	@Deprecated
	protected boolean isValidJsonpQueryParam(String value) {
		return CALLBACK_PARAM_PATTERN.matcher(value).matches();
	}

	/**
	 * Filter out undesired attributes from the given model.
	 * The return value can be either another {@link Map} or a single value object.
	 * <p>The default implementation removes {@link BindingResult} instances and entries
	 * not included in the {@link #setModelKeys modelKeys} property.
	 *
	 * @param model the model, as passed on to {@link #renderMergedOutputModel}
	 * @return the value to be rendered
	 */
	protected Object filterModel(Map<String, Object> model) {
		Map<String, Object> result = new HashMap<>(model.size());
		Set<String> modelKeys = (!CollectionUtils.isEmpty(this.modelKeys) ? this.modelKeys : model.keySet());
		model.forEach((clazz, value) -> {
			if (!(value instanceof BindingResult) && modelKeys.contains(clazz)) {
				result.put(clazz, value);
			}
		});
		return (this.extractValueFromSingleKeyModel && result.size() == 1 ? result.values().iterator().next() : result);
	}

	@Override
	protected void setResponseContentType(HttpServletRequest request, HttpServletResponse response) {
		if (getJsonpParameterValue(request) != null) {
			response.setContentType(DEFAULT_JSONP_CONTENT_TYPE);
		} else {
			super.setResponseContentType(request, response);
		}
	}

	@Override
	protected void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
		Object value = filterModel(model);
		response.getWriter().write(JSONObject.toJSONString(value));
	}
}