http断点续传简单实现（java)

/* aqk0+  
**SiteFileFetch.java <,!e*V*U  
*/ LJAqk2k  
package NetFox; KK%R3{  
import java.io.*; 58@YWvAk  
import java.net.*; 6RLYpQ$+  
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public class SiteFileFetch extends Thread { BB694   
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SiteInfoBean siteInfoBean = null; //文件信息Bean <!s+X_^  
long[] nStartPos; //开始位置 :d ts>  
long[] nEndPos; //结束位置 8(Ab NQ  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 +I {ZW}rA  
long nFileLength; //文件长度 D 1Q@4 g  
boolean bFirst = true; //是否第一次取文件 TUQ+?[  
boolean bStop = false; //停止标志
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File tmpFile; //文件下载的临时信息 uoM;p'  
DataOutputStream output; //输出到文件的输出流 8i=c|k,GL.  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） *?a rEYc8  
public SiteFileFetch(SiteInfoBean bean) throws IOException b!7*bFTt  
{ 5mxYzu;#]  
siteInfoBean = bean; u._B7R&>  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); `EUufTYi
 
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); &]'{N69@d?  
if(tmpFile.exists ()) oWu2}#~z_  
{ T5g}z5~"  
bFirst = false; x9s7:F  
read_nPos(); =skw@c^  
} :QGd/JX$n`  
else 2|KgRk|!  
{ V kA$T8  
nStartPos = new long[bean.getNSplitter()]; [!ghI%VK  
nEndPos = new long[bean.getNSplitter()]; LK}Ih@f  
} &G)I|mv  
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} ZPieL&uV`  
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public void run() L"|~,
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{  jIMT&5k  
//获得文件长度 K/,y"DUN&  
//分割文件 s\k4<d5  
//实例FileSplitterFetch H6Mqy}4W  
//启动FileSplitterFetch线程 E,S[3+  
//等待子线程返回 6V"|  
try{ QgZwU$`p0  
if(bFirst) o"te7nBI  
{ "%o,P/<X  
nFileLength = getFileSize(); =ZE]jmD4P  
if(nFileLength == -1) Nq`@ >Ml  
{ HH-A\#6J  
System.err.println("File Length is not known!"); 4&}V
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} ~$GRgOn  
else if(nFileLength == -2) ''{REFjK7  
{ vr,8i7*0  
System.err.println("File is not access!"); [z2XK4\e1T  
} bjQp6!TsZ  
else u?(@hUV.  
{ TY(B]Q_o  
for(int i=0;i<nStartPos.length;i++) raWs6b4Q  
{ Kw`{B3"  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 0W92Z@_GY  
} ,cgFdOM.  
for(int i=0;i<nEndPos.length-1;i++) e;+6U"Jx*  
{ MX@t[{Gg9  
nEndPos = nStartPos[i+1]; :!SVpCt3  
} Wchu-]  
nEndPos[nEndPos.length-1] = nFileLength; toq/G,N Q  
} @H{QHi  
} NUlp4i~Q  
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//启动子线程 i++a^f  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; $pV:)N4  
for(int i=0;i<nStartPos.length;i++) YP^=b}  
{ JHxy_<p/  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), /s@t-gTi  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 4pvT?s>68  
nStartPos,nEndPos,i); w\"~*(M  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); -C]k
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fileSplitterFetch.start(); #41xzN  
} 9O8na 'w  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), /6=IL  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); Vs[A  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", ',7LVT7  
nEndPos = " + nFileLength); eGwO!Lv}B  
// fileSplitterFetch[nPos.length-1].start(); Mnu8d:$  
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//等待子线程结束 p<eu0B_
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//int count = 0; `!`g&:Y  
//是否结束while循环 }V:B,:  
boolean breakWhile = false; ''bh{ .x  

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while(!bStop) z\d{A7  
{ 8#m,TOp  
write_nPos(); InO;DA\  
Utility.sleep(500); !"v[\||1  
breakWhile = true;  Re=()M  
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for(int i=0;i<nStartPos.length;i++) !lVOZ%  
{ 'YKzs;y$  
if(!fileSplitterFetch.bDownOver) )x!b{5'"7  
{ Xkqq$A4  
breakWhile = false; Uuxx^>"h\  
break; PBeBI:  
} Su]@~^w  
} sf([8YUd  
if(breakWhile) #r=Jc8J_  
break; 6'{/Ote  
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//count++; 6`PQP;
 
//if(count>4) Q#Tg)5.\  
// siteStop(); (#&-ld6  
} m4 k:uk7N  
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System.err.println("文件下载结束！"); 5NR@<FE  
} H[S}&l\D4  
catch(Exception e){e.printStackTrace ();} ,QeJ;U  
} ->^Ex`  
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//获得文件长度 w)rd--9f  
public long getFileSize() (-no
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{ 5}3#l/  
int nFileLength = -1; P<
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try{ W\c1QY$E  
URL url = new URL(siteInfoBean.getSSiteURL()); _o52#Q4   
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); %(uYYr 6  
httpConnection.setRequestProperty("User-Agent","NetFox"); xekU2u}WE  
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int responseCode=httpConnection.getResponseCode(); ,qT^e8E+  
if(responseCode>=400) 5K:'VX  
{ .E:3I!dH7  
processErrorCode(responseCode); gW5yLb_Vz$  
return -2; //-2 represent access is error u|mTF>L  
} VLfc6:Yg  
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String sHeader; `SH14
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for(int i=1;;i++) ;!+-fn4C  
{ %lnVzGP  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); lR>p  
//Utility.log(in.readLine()); EKD?
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sHeader=httpConnection.getHeaderFieldKey(i); Ob&m&2
s,  
if(sHeader!=null) DFXHD,o  
{ ELN1F0TneH  
if(sHeader.equals("Content-Length")) )n&6= Li  
{ M!/!*,~  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); g5C$#<28  
break; mDXG~*1  
} \8Hs[H!  
} `53S[8  
else ri`;   
break; U*:ju+)k  
} 5SMV3~*P  
}
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catch(IOException e){e.printStackTrace ();} 9Tg k=  
catch(Exception e){e.printStackTrace ();} w:pPd;nz0Y  
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Utility.log(nFileLength); 9/`3=r@  
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return nFileLength; J
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} `6P2+wf1j~  
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//保存下载信息（文件指针位置） c{IL"B6>  
private void write_nPos()
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{ vGnFX0?h  
try{ sd"eu  
output = new DataOutputStream(new FileOutputStream(tmpFile)); s f.z(o  
output.writeInt(nStartPos.length); |[0Ijm2  
for(int i=0;i<nStartPos.length;i++) !' 0PM[  
{ sPMICIv|  
// output.writeLong(nPos); o`Af6C;Q  
output.writeLong(fileSplitterFetch.nStartPos); WH"'Ju5}  
output.writeLong(fileSplitterFetch.nEndPos); 0CvGpM,  
} $NCR V:J  
output.close(); L]%!YP\<T  
} ts% n tnvI  
catch(IOException e){e.printStackTrace ();} J(K/z,4h  
catch(Exception e){e.printStackTrace ();} Eg&:yF}?(  
} nLOK1@,4  
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//读取保存的下载信息（文件指针位置） _^eiN'B  
private void read_nPos() &Z3%UOY  
{ ;B;@MD,B  
try{ xC9{hXg!  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); omGzyuPF  
int nCount = input.readInt(); 5JEOLPS
  
nStartPos = new long[nCount]; j{'_sI{{  
nEndPos = new long[nCount]; ;5.<M<PH  
for(int i=0;i<nStartPos.length;i++) cIQbu#[@  
{ o>nw~_ H\  
nStartPos = input.readLong(); >tPf.xI|l  
nEndPos = input.readLong(); XjCx`bX^<  
} 4x&Dz0[[S  
input.close(); +$#<gp"  
} 5|~nX8>  
catch(IOException e){e.printStackTrace ();} oc]:Ty  
catch(Exception e){e.printStackTrace ();} 2S~(P  
} |5%T)  

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private void processErrorCode(int nErrorCode) +ue1+#  
{ |/H?\]7  
System.err.println("Error Code : " + nErrorCode); X.S<",a{qz  
} NtM ?Jh  
/g.c(-#]  
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//停止文件下载 VBix8|  
public void siteStop() u8.Tu7~  
{
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bStop = true; Hi=</ Wy;  
for(int i=0;i<nStartPos.length;i++) W6}>iB  
fileSplitterFetch.splitterStop(); akNqSZwj  
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} S<NK!89  
} qPD(D{,f$  
//负责部分文件的抓取 \?R#ZxP@  
**FileSplitterFetch.java \/<VJB uV  
*/ i0$*):b  
package NetFox; w&p(/y  
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import java.io.*; ,pI9=e@O/z  
import java.net.*; RqGX(Iuv  
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public class FileSplitterFetch extends Thread { 1s@QsZ3  
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String sURL; //File URL [ 5}Q  
long nStartPos; //File Snippet Start Position `j@1]%&z  
long nEndPos; //File Snippet End Position pXl[I;  
int nThreadID; //Thread's ID nOL.%  
boolean bDownOver = false; //Downing is over 6QY;t:/<  
boolean bStop = false; //Stop identical y)&K9 I  
FileAccessI fileAccessI = null; //File Access interface D0xQXC3$`  
:K]7(y7>  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException 9/29>K_  
{ aH{)|?  
this.sURL = sURL; @9KW ]7  
this.nStartPos = nStart; y`buY+5l  
this.nEndPos = nEnd; |mQ Fi\  
nThreadID = id; \ m~?yq8H  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 i,*m(C@F}  
} ) yMrET m  
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 &Q~W{.  
public void run() k*fU:q1  
{ \(P?=] -  
while(nStartPos < nEndPos && !bStop) 9%T"W  
{ zZCRej  
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try{ 6EyPZ{  
URL url = new URL(sURL); >[|N%9\  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); rvd$4l^  
httpConnection.setRequestProperty("User-Agent","NetFox"); q%dG>!  
String sProperty = "bytes="+nStartPos+"-"; +,>%Yb=EA  
httpConnection.setRequestProperty("RANGE",sProperty); dn- [Gnde  
Utility.log(sProperty); xrg?{*\  
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InputStream input = httpConnection.getInputStream(); 0Xh_.PF  
//logResponseHead(httpConnection); D:/ n2_  
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byte[] b = new byte[1024]; t Y  
int nRead; Lkm-<  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) R}=5:)%w  
{ DQXUh#t\(]  
nStartPos += fileAccessI.write(b,0,nRead); ResU5Ce~  
//if(nThreadID == 1) M@A3+v%K  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); pd'0|  
} yv[j Pbe  
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/]TNEU,K  
Utility.log("Thread " + nThreadID + " is over!"); I
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bDownOver = true; fkzSX8a9}  
//nPos = fileAccessI.write (b,0,nRead); ccuGM WG*  
} (G"'Fb6d  
catch(Exception e){e.printStackTrace ();} sW]^YT>?  
} 2nB99L{6  
} .*z
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//打印回应的头信息 LlQsc{Ddf  
public void logResponseHead(HttpURLConnection con) S 5S\zTPIf  
{ 4qOzjEQ
 
for(int i=1;;i++) O^@8Drg
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{ "<ZV'z  
String header=con.getHeaderFieldKey(i); gpV4qDXV  
if(header!=null) c|Ivet>3  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); r[L%ap\{  
Utility.log(header+" : "+con.getHeaderField(header));
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else 7]h%?W!  
break; ]ZY2\'  
} 9jkz83/+<  
} 7=l~fKu  
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public void splitterStop() )/;KxaKt  
{ OsgPNy0  
bStop = true; o^"+X7)  
} ;'"'|} xn  
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} cbzA`b'Mg  
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/* @?,x3\N-  
**FileAccess.java  =z.j{%  
*//文件访问(定位，写) :5t4KcQ  
package NetFox; !7N:cx'Qy  
import java.io.*; E'QAsU8pP  
5 D|#l*V  
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public class FileAccessI implements Serializable{ .hT>a<  
O =Z}DGa+  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 .a%6A#<X  
RandomAccessFile oSavedFile; *[Hp&6f  
long nPos; dAI^P/y%  
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public FileAccessI() throws IOException _{*}
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{ 7>Scf  
this("",0); Y 6a`{'  
} wLV,E,gM  
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public FileAccessI(String sName,long nPos) throws IOException W5|{A])N  
{ "#d$$ 8  
oSavedFile = new RandomAccessFile(sName,"rw"); 9[eiN  
this.nPos = nPos; V6g*
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oSavedFile.seek(nPos); 2q?/aw ;Z  
} {53FR  
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529;_|  
public synchronized int write(byte[] b,int nStart,int nLen) VUP|j/qD  
{ 1c$pz:$vX  
int n = -1; o@Ye_aM~?Y  
try{ 1[egCC\Mo_  
oSavedFile.write(b,nStart,nLen); mv9D{_,pD  
n = nLen; -)A:@+GF  
} t^#1=nK  
catch(IOException e) +t7HlAXB#  
{ IFLphm
5  
e.printStackTrace (); ql?w6qFs]  
} $(1t~u<17  
{v"f){   
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return n; WIWo4[(  
} m#+0m!  
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} *l7 `
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/* 5gz^3R|`f  
**SiteInfoBean.java a~2Jf @I3  
*/ I
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package NetFox; rJ/HIda  
o$@/@r  
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public class SiteInfoBean { g`y9UYeh  
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private String sSiteURL; //Site's URL jOhAXe;~X{  
private String sFilePath; //Saved File's Path ` nX,x-UM  
private String sFileName; //Saved File's Name =Uk#7U"P  
private int nSplitter; //Count of Splited Downloading File ra~=i|s  
4"
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public SiteInfoBean() w
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{//nSplitter的缺省值为5 '6D"QDZB  
//default value of nSplitter is 5 c&;" Y{  
this("","","",5); dv. 77q  
} ?y|&Mz'XJ(  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) aT^ $'_ G  
{ B7Ket8<J  
sSiteURL= sURL; sI\NX$M  
sFilePath = sPath; jTwSyW  
sFileName = sName; +[}y` -t  
this.nSplitter = nSpiltter; PTHxvml  
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} t__f=QB/  
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public String getSSiteURL() .BxI~d^  
{ #8jiz+1 _  
return sSiteURL; WX Fm'5Vr  
} W~H`{x%Av>  
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public void setSSiteURL(String value) A^lm0[3q  
{ 9>{ml&$  
sSiteURL = value; @+;.W>^h  
} #~Xj=M%
 
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) `{jPK*`  
public String getSFilePath() /yU#UZ4;  
{ =U84*HAv  
return sFilePath; f['I4 /o  
} nZiwR4kM  
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public void setSFilePath(String value) YUSrZ9Yg  
{ P^o@x,V!&  
sFilePath = value; ttr`  
} T=NLBJ  
*v#V%_o  
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public String getSFileName() @oY+b!L  
{ w[a(I}x  
return sFileName; i^WY/ OhL  
} ]9_t
to!/  
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public void setSFileName(String value) !,$K;L  
{ nK< v
  
sFileName = value; xd `MEOY  
} L'Iw9RAJ  
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public int getNSplitter() F<h+d917  
{ fAkfNH6  
return nSplitter; U=%(kOx  
} :~vg'v~C  
{KDN|o+%  
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public void setNSplitter(int nCount) =LY`K#  
{ 9PV]bt,  
nSplitter = nCount; ,XscO7  
} N, u]2,E  
} O\uI
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/* ;4dFL\KU  
**Utility.java h#Rza-?"\  
*/ Slo^tqbG  
package NetFox; }>y!I5O  
@=z.^I30  
M_+W5Gz<  
public class Utility { aZo}Ix:/  
{o^tSEN!-
 
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public Utility() a Z)1SX`D  
{ Q"NZE  
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} }; 7I   
"]2^O  
//线程睡眠 2Y9u9;ah  
public static void sleep(int nSecond) Q)XH5C2X  
{ #?\(l%  
try{ ->OVNmCB`+  
Thread.sleep(nSecond); uDJ;GD[yc  
} ]5@n`;&#.  
catch(Exception e) 2::YR?  
{ H;<>uELie  
e.printStackTrace (); &2.DZ),L  
} y4@gw.pt  
} GzaGTd.b  
5~UW=   
//日志 w*~s&7c2B  
public static void log(String sMsg) nVoWER:  
{ `<~=6H  
System.err.println(sMsg); OqRRf  
} wjH1Ombt  
:J@3:+sr  
:81d~f7  
public static void log(int sMsg) w\D !e  
{ PRUl-v  
System.err.println(sMsg); p-\->_9)y`  
} $nW9VMa  
} |ssl0/nk  
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/* ?%~^PHgZ|  
**TestMethod.java dR_6j}  
*/ NZZy^p&O  
package NetFox; p/nATvh$  
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public class TestMethod { 5y g`

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9,JM$ Y {  
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public TestMethod() m44a HBwId  
{ ///xx/weblogic60b2_win.exe Ye$j43b  
try{ }@t"B9D  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); {
K"hlu[  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); OE0G*`m  
SiteFileFetch fileFetch = new SiteFileFetch(bean); g"|>^90  
fileFetch.start(); N>*+Wg$Ne  
} zdU46|!u  
catch(Exception e){e.printStackTrace ();} _4)z:?G5  
1,) yEeHjU  
^<-r57pz  
} V7nOT*N:Q  
(&Lt&i _  
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public static void main(String[] args) 3TCRCz  
{ %c\kLSe  
new TestMethod(); *-5N0K<kQ  
} 9`N5$;NzY  
} AnX<\7bc}  
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