模板引擎除了去做后端应用的页面渲染，很多时候也可以用来生成一些代码，例如利用sql生成pojo对象，生成模板页面等
这里简单记录一下Velocity渲染模板时最基本的代码
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引入Velocity Maven信息
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10<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity</artifactId>
<version>1.7</version>
</dependency>
<dependency>
<groupId>org.apache.velocity</groupId>
<artifactId>velocity-tools</artifactId>
<version>2.0</version>
</dependency> -
实现代码
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51import com.google.common.base.Charsets;
import com.google.common.collect.Maps;
import com.github.pdf.tools.exception.VelocityException;
import net.sf.cglib.beans.BeanMap;
import org.apache.velocity.Template;
import org.apache.velocity.VelocityContext;
import org.apache.velocity.app.Velocity;
import org.apache.velocity.app.VelocityEngine;
import java.io.StringWriter;
import java.util.Collections;
import java.util.Map;
import java.util.Objects;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
* @author wangdongbo
* @since 2019/7/3.
*/
public class extends AbstractTemplate {
private static final Map<String, VelocityEngine> ENGINE_MAP = new ConcurrentHashMap<>(16);
private static VelocityEngine getEngine(String templatePath) {
if (ENGINE_MAP.containsKey(templatePath)) {
return ENGINE_MAP.get(templatePath);
}
Properties properties = new Properties();
properties.setProperty(Velocity.OUTPUT_ENCODING, Charsets.UTF_8.toString());
properties.setProperty(Velocity.INPUT_ENCODING, Charsets.UTF_8.toString());
properties.setProperty(Velocity.FILE_RESOURCE_LOADER_PATH, templatePath);
VelocityEngine velocityEngine = new VelocityEngine(properties);
ENGINE_MAP.put(templatePath, velocityEngine);
return velocityEngine;
}
protected String getContent(String templatePath, String templateName, Object data) {
try {
VelocityContext velocityContext = new VelocityContext(Objects.nonNull(data) ? Maps.newHashMap(BeanMap.create(data)) : Collections.emptyMap());
Template template = getEngine(templatePath).getTemplate(templateName, Charsets.UTF_8.toString());
StringWriter writer = new StringWriter();
template.merge(velocityContext, writer);
writer.flush();
return writer.toString();
} catch (Exception e) {
throw new VelocityException("Velocity exception", e);
}
}
}
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