spring mvc view resolver

迷南。 2022-08-26 14:11 65阅读 0赞

根据不同的请求后缀返回不同的View

例如：/test.xml 返回xml数据，/test.json 返回Json数据

package com.lss.web.controller;
    
    import javax.servlet.http.HttpServletRequest;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Controller;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.servlet.ModelAndView;
    
    import com.lss.web.viewresolver.MultipleViewResolver;
    
    @Controller
    public class ResolverController {
    	@Autowired
    	private MultipleViewResolver resolver;
    
    	@RequestMapping("/test")
    	public String test() {
    		return "test";
    	}
    
    	@RequestMapping("/test.json")
    	public String testJson() {
    		return "test.json";
    	}
    
    	@RequestMapping("/test.xml")
    	public String getSampleJsp() {
    		return "test.xml";
    	}
    
    	@RequestMapping(value = "/test1")
    	public ModelAndView test1(HttpServletRequest request, ModelAndView mv) {
    		mv.setViewName("test" + getPostfix(request));
    		return mv;
    	}
    
    	private String getPostfix(HttpServletRequest request) {
    		String uri = request.getRequestURI();
    		if (uri.indexOf(".") != -1) {
    			String postfix = uri.substring(uri.indexOf(".") + 1);
    			if (resolver.checkPostfix(postfix)) {
    				return "." + postfix;
    			}
    		}
    		return "";
    	}
    }

package com.lss.web.view;
    
    import java.util.Map;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import org.springframework.web.servlet.view.AbstractUrlBasedView;
    
    public class GenericFileView extends AbstractUrlBasedView {
    
    	// default content type
    	private final static String CONTENT_TYPE = "text/plain";
    
    	// content of http response
    	private String responseContent;
    
    	public GenericFileView() {
    		super();
    		setContentType(CONTENT_TYPE);
    	}
    
    	@Override
    	public void setContentType(String contentType) {
    		super.setContentType(contentType);
    	}
    
    	@Override
    	protected void renderMergedOutputModel(Map<String, Object> model, HttpServletRequest request, HttpServletResponse response) throws Exception {
    		response.setContentType(getContentType());
    		response.getWriter().write(this.responseContent);
    		response.getWriter().close();
    	}
    
    	/**
    	 * Set http request content
    	 * 
    	 * @param responseContent
    	 */
    	public void setResponseContent(String responseContent) {
    		this.responseContent = responseContent;
    	}
    
    }
    
    
    
    
     
     
     package com.lss.web.viewresolver;
    
    import java.io.ByteArrayOutputStream;
    import java.io.InputStream;
    import java.util.Locale;
    import java.util.logging.Logger;
    
    import org.springframework.core.Ordered;
    import org.springframework.core.io.Resource;
    import org.springframework.web.servlet.View;
    import org.springframework.web.servlet.view.AbstractCachingViewResolver;
    
    import com.lss.web.view.GenericFileView;
    
    public class GenericFileViewResolver extends AbstractCachingViewResolver implements Ordered {
    
    	private Logger logger = Logger.getLogger(GenericFileViewResolver.class.getName());
    
    	private int order = Integer.MIN_VALUE;
    
    	// requested file location under web app
    	private String location;
    
    	private String viewName;
    
    	public void setViewName(String viewName) {
    		this.viewName = viewName;
    	}
    
    	public void setOrder(int order) {
    		this.order = order;
    	}
    
    	public void setLocation(String location) {
    		this.location = location;
    	}
    
    	public int getOrder() {
    		return this.order;
    	}
    
    	@Override
    	protected View loadView(String viewName, Locale locale) throws Exception {
    		if (location == null) {
    			throw new Exception("No location specified for GenericFileViewResolver.");
    		}
    		String requestedFilePath = location + viewName;
    		Resource resource = null;
    		// String url = "";
    		try {
    			logger.finest(requestedFilePath);
    			resource = getApplicationContext().getResource(requestedFilePath);
    			// url = resource.getURI().toString();
    		} catch (Exception e) {
    			// this exception should be catched and return null in order to call
    			// next view resolver
    			logger.finest("No file found for file: " + requestedFilePath);
    			return null;
    		}
    		logger.info("Requested file found: " + requestedFilePath + ", viewName:" + viewName);
    		// get view from application content, scope=prototype
    		GenericFileView view = this.getApplicationContext().getBean(this.viewName, GenericFileView.class);
    		view.setUrl(requestedFilePath);
    		view.setResponseContent(inputStreamToString(resource.getInputStream(), "UTF-8"));
    		return view;
    	}
    
    	final static int BUFFER_SIZE = 4096;
    
    	/**
    	 * Convert Input to String based on specific encoding
    	 * 
    	 * @param in
    	 * @param encoding
    	 * @return
    	 * @throws Exception
    	 */
    	public static String inputStreamToString(InputStream in, String encoding) throws Exception {
    		ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    		byte[] data = new byte[BUFFER_SIZE];
    		int count = -1;
    		while ((count = in.read(data, 0, BUFFER_SIZE)) != -1)
    			outStream.write(data, 0, count);
    
    		data = null;
    		return new String(outStream.toByteArray(), encoding);
    	}
    
    }
    
    
     package com.lss.web.viewresolver;
    
    import java.util.Locale;
    import java.util.Map;
    
    import org.springframework.core.Ordered;
    import org.springframework.util.StringUtils;
    import org.springframework.web.servlet.View;
    import org.springframework.web.servlet.ViewResolver;
    import org.springframework.web.servlet.view.AbstractCachingViewResolver;
    
    public class MultipleViewResolver extends AbstractCachingViewResolver implements Ordered {
    
    	private int order = Integer.MIN_VALUE;
    
    	public int getOrder() {
    		return order;
    	}
    
    	public void setOrder(int order) {
    		this.order = order;
    	}
    
    	private Map<String, ViewResolver> resolvers;
    
    	public void setResolvers(Map<String, ViewResolver> resolvers) {
    		this.resolvers = resolvers;
    	}
    
    	@Override
    	protected View loadView(String viewName, Locale locale) throws Exception {
    		String fileExtension = StringUtils.getFilenameExtension(viewName);
    		// return null to invoke next resolver if no extension found
    		if (fileExtension == null) {
    			return null;
    		}
    		// get resolver by extension
    		ViewResolver resolver = resolvers.get(fileExtension);
    		// return null to invoke next resolver if no resolver found
    		return resolver == null ? null : resolver.resolveViewName(viewName, locale);
    
    	}
    
    	public boolean checkPostfix(String postfix) {
    		return resolvers.containsKey(postfix);
    	}
    
    }

将以下配置假如到Servlet.XML

<beanid=*"viewResolver"*

class=*"com.lss.web.viewresolver.MultipleViewResolver"*p:order=*"0"*>

<propertyname=*"resolvers"*>

<map>

<beanclass=*"com.lss.web.viewresolver.GenericFileViewResolver"*

p:location=*"/WEB-INF/json/"* p:cache=*"false"*>

</bean>

</entry>

<beanclass=*"com.lss.web.viewresolver.GenericFileViewResolver"*

p:location=*"/WEB-INF/xml/"* p:cache=*"false"*>